Moving picture coding method, moving picture decoding method, moving picture coding apparatus, moving picture decoding apparatus, and moving picture coding and decoding apparatus

ABSTRACT

A moving picture coding includes: coding a first flag indicating whether or not temporal motion vector prediction is used; when the first flag indicates that the temporal motion vector prediction is used: coding a first parameter for calculating the temporal predictive motion vector; wherein when the first flag indicates that the temporal motion vector prediction is not used, the first parameter is not coded.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. Provisional PatentApplication No. 61/607,028 filed Mar. 6, 2012. The entire disclosure ofthe above-identified application, including the specification, drawingsand claims is incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to a moving picture coding method and amoving picture decoding method.

BACKGROUND

In the moving picture coding process, the amount of data is compressedusing redundancy of a moving picture in a spatial direction and atemporal direction in general. A transformation into a frequency domainis generally used as a method for using the redundancy in the spatialdirection. In addition, as a way to use the redundancy in the temporaldirection, an inter-picture prediction (hereafter referred to as aninter prediction) coding is used (for example, see the Non-PatentLiterature 1).

CITATION LIST Non Patent Literature

-   [Non-Patent Literature 1] ITU-T Recommendation H.264 “Advanced Video    Coding for Generic Audiovisual Services” March, 2010

SUMMARY Technical Problem

In the moving picture coding method and the moving picture decodingmethod, improvement on coding efficiency is desired.

One non-limiting and exemplary embodiment provides a moving picturecoding method and a moving picture decoding method capable of improvingthe coding efficiency.

Solution to Problem

One non-limiting and exemplary embodiment provides a moving picturecoding method includes coding a first flag indicating whether or nottemporal motion vector prediction using a temporal motion vectorpredictor which is a motion vector of a block included in a codedpicture different from the current picture is used; when the first flagindicates that the temporal motion vector prediction is used: coding afirst parameter for calculating the temporal motion vector predictor;deriving, using the first parameter, a plurality of first motion vectorpredictor candidates including the temporal motion vector predictor;coding a motion vector used for performing inter predictive coding onthe current block, using one of the first motion vector predictorcandidates; when the first flag indicates that the temporal motionvector prediction is not used: deriving a plurality of second motionvector predictor candidates that do not include the temporal motionvector predictor; and coding a motion vector used for performing interpredictive coding on the current block, using one of the second motionvector predictor candidates, wherein when the first flag indicates thatthe temporal motion vector prediction is not used, the first parameteris not coded.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Advantageous Effects

The present disclosure provides a moving picture coding method and amoving picture decoding method capable of improving the codingefficiency.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

FIG. 1 is a diagram for describing a motion vector in a temporal motionvector prediction.

FIG. 2 is a block diagram of a moving picture coding apparatus accordingto the embodiment 1.

FIG. 3 is a diagram illustrating an overview of process flow of a movingpicture coding method according to the embodiment 1.

FIG. 4 illustrates an example of motion vector predictor candidatesaccording to the embodiment 1.

FIG. 5 illustrates an example of list of codes when performing variablelength coding on a motion vector predictor index according to theembodiment 1.

FIG. 6 is a diagram illustrating flow for determining motion vectorpredictor candidates according to the embodiment 1.

FIG. 7 is a conceptual diagram illustrating reading/writing processto/from a colPic memory and a global vector storage unit according tothe embodiment 1.

FIG. 8A illustrates a detailed process flow of S11 in FIG. 3 accordingto the embodiment 1.

FIG. 8B is a diagram illustrating an example of B pictures referred toby other pictures according to the embodiment 1.

FIG. 9 illustrates a detailed process flow of S17 in FIG. 3 according tothe embodiment 1.

FIG. 10 illustrates a detailed process flow of S13 and S14 in FIG. 3according to the embodiment 1.

FIG. 11A illustrates an example of method for deriving a motion vectorpredictor candidate using a forward reference motion vector according tothe embodiment 1.

FIG. 11B illustrates an example of method for deriving a motion vectorpredictor candidate using a backward reference motion vector accordingto the embodiment 1.

FIG. 12A illustrates an example of method for deriving a motion vectorpredictor candidate using a backward reference motion vector accordingto the embodiment 1.

FIG. 12B illustrates an example of method for deriving a motion vectorpredictor candidate using a forward reference motion vector according tothe embodiment 1.

FIG. 13 is a diagram illustrating process flow of a moving picturecoding method according to the embodiment 1.

FIG. 14 is a diagram illustrating process flow of a moving picturecoding method according to the embodiment 1.

FIG. 15 is a block diagram of a moving picture decoding apparatusaccording to the embodiment 2.

FIG. 16 is a diagram illustrating an overview of process flow of amoving picture decoding method according to the embodiment 2.

FIG. 17 is a diagram illustrating syntax of a bitstream in the movingpicture decoding method according to the embodiment 2.

FIG. 18 is a diagram illustrating process flow of a moving picturedecoding method according to the embodiment 2.

FIG. 19A is a diagram illustrating an example of syntax according to theembodiment 2.

FIG. 19B is a diagram illustrating an example of syntax according to theembodiment 2.

FIG. 20 is a diagram illustrating an example of syntax according to theembodiment 2.

FIG. 21 is a diagram illustrating process flow of a moving picturedecoding method according to the embodiment 2.

FIG. 22 is a block diagram of a moving picture coding apparatusaccording to the variation of the embodiment 1.

FIG. 23 is a flowchart illustrating actions in the moving picture codingmethod according to the variation of the embodiment 1.

FIG. 24 illustrates an example of an image including base view anddependent view, according to the variation of the embodiment 2.

FIG. 25 is a block diagram of a moving picture decoding apparatusaccording to the variation of the embodiment 2.

FIG. 26 illustrates an overall configuration of a content providingsystem ex190 for implementing content distribution services.

FIG. 27 illustrates an overall configuration of a digital broadcastingsystem.

FIG. 28 illustrates a block diagram illustrating an example of aconfiguration of a television.

FIG. 29 illustrates a block diagram illustrating an example of aconfiguration of an information reproducing/recording unit that readsand writes information from and on a recording medium that is an opticaldisk.

FIG. 30 illustrates an example of a configuration of a recording mediumthat is an optical disk.

FIG. 31A illustrates an example of a cellular phone.

FIG. 31B is a block diagram showing an example of a configuration of acellular phone.

FIG. 32 illustrates a structure of multiplexed data.

FIG. 33 schematically illustrates how each stream is multiplexed inmultiplexed data.

FIG. 34 illustrates how a video stream is stored in a stream of PESpackets in more detail.

FIG. 35 illustrates a structure of TS packets and source packets in themultiplexed data.

FIG. 36 illustrates a data structure of a PMT.

FIG. 37 illustrates an internal structure of multiplexed datainformation.

FIG. 38 illustrates an internal structure of stream attributeinformation.

FIG. 39 illustrates steps for identifying video data.

FIG. 40 illustrates an example of a configuration of an integratedcircuit for implementing the moving picture coding method and the movingpicture decoding method according to each of Embodiments.

FIG. 41 illustrates a configuration for switching between drivingfrequencies.

FIG. 42 illustrates steps for identifying video data and switchingbetween driving frequencies.

FIG. 43 shows an example of a look-up table in which video datastandards are associated with the driving frequencies.

FIG. 44A is a diagram showing an example of a configuration for sharinga module of a signal processing unit.

FIG. 44B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENT(S)

(Underlying Knowledge of the Present Disclosure)

The inventors found out the following problem concerning theconventional technology.

When performing inter predictive coding on a picture, the moving picturecoding apparatus uses a coded picture preceding or following the currentpicture in display order (display time order) as a reference picture.Subsequently, the moving picture coding apparatus derives a motionvector by motion estimation of the current picture with respect to thereference picture, and calculates a difference between the predictiveimage data obtained by performing motion compensation based on themotion vector and the image data of the current picture. This eliminatesredundancy in temporal direction. When estimating motion, the movingimage coding apparatus calculates a difference value between the currentblock in the current picture and a block in the reference picture, andselects a block in a reference picture having a smallest differencevalue as the reference block. Subsequently, the moving image codingapparatus estimates the motion vector using the current block and thereference block.

In a standardized moving picture coding method referred to as H.264,three types of pictures, that is, I picture, P picture, and B pictureare used for compressing the amount of data. I picture is a picture onwhich no inter predictive coding is performed; that is, only intrapicture prediction (hereinafter referred to as intra prediction) isperformed. P picture is a picture on which the inter predictive codingis performed by referring only one coded picture preceding or followingthe current picture in display order. B picture is a picture on whichthe inter predictive coding is performed by referring two coded picturespreceding or following the current picture in display order.

In the moving picture coding method referred to as H.264, a motionvector estimation mode for coding a motion vector used for generating adifference value between the predictive image data and the current blockand a motion vector used for generating the predictive image data isused as a mode for inter predictive coding on the current block for Bpictures. In the motion vector estimation mode, the moving image codingapparatus can select, as the prediction direction, either abi-prediction for generating a predictive image by referring to twocoded pictures preceding or following the current picture or auni-prediction for generating a predictive image by referring to onecoded picture preceding or following the current picture.

Furthermore, in the moving picture coding method referred to as H.264,the moving picture coding apparatus can select a coding mode referred toas temporal motion vector prediction (temporal motion vector predictormode or temporal direct mode) when deriving a motion vector for coding aB picture. A motion vector predictor generated by temporal motion vectorprediction (motion vector predictor candidate) is referred to as atemporal motion vector predictor.

The inter predictive coding method in temporal motion vector predictionshall be described with reference to FIG. 1. FIG. 1 is an explanatorydiagram illustrating motion vectors in temporal motion vectorprediction, and illustrates a case where a block a in the picture B2 iscoded by temporal motion vector prediction.

In this case, a motion vector vb in the picture P3 which is a referencepicture subsequent to the picture B2 in the same location as the block ais used. The motion vector vb is a motion vector used for coding theblock b, and refers to the picture P1. Subsequently, the moving picturecoding apparatus obtains a reference block from a picture P1, a forwardreference picture, and from a picture P3, a backward reference picture,and codes the block a by bi-prediction. To put it differently, themotion vector used for coding the block a is a motion vector va1 withregard to the picture P1, and is a motion vector va2 with regard to thepicture P3.

However, in the temporal motion vector prediction, the information on areference picture having information on motion vector and others usedfor calculating the temporal motion vector predictor is lost due topacket loss in streaming distribution, for example, a decoded image isdegraded since the correct temporal motion vector predictor cannot becalculated. Furthermore, an error is propagated to a picture whichrefers to the decoded image, and the decoding process may stop as aresult. For example, when the information on the reference picture P3 inFIG. 1 is lost, the temporal motion vector predictor for the picture B2cannot be calculated. As a result, there is a case in which the pictureB2 is not correctly decoded and the decoding process stops.

In response to this problem, the moving picture coding method and themoving picture decoding method capable of preventing the propagation oferror in decoding shall be described in this embodiment.

In the moving picture coding method and the moving picture decodingmethod, improvement on coding efficiency is desired. Accordingly, inthis embodiment, a moving picture coding method and a motion picturedecoding method capable of improving the coding efficiency shall bedescribed.

In the moving picture coding method according to an aspect of thepresent disclosure, moving picture coding method for coding a currentblock to be coded included in a current picture to be coded by interpredictive coding using a motion vector, the moving picture codingmethod includes: coding a first flag indicating whether or not temporalmotion vector prediction using a temporal motion vector predictor whichis a motion vector of a block included in a coded picture different fromthe current picture is used; when the first flag indicates that thetemporal motion vector prediction is used: coding a first parameter forcalculating the temporal motion vector predictor; deriving, using thefirst parameter, a plurality of first motion vector predictor candidatesincluding the temporal motion vector predictor; coding a motion vectorused for performing inter predictive coding on the current block, usingone of the first motion vector predictor candidates; when the first flagindicates that the temporal motion vector prediction is not used:deriving a plurality of second motion vector predictor candidates thatdo not include the temporal motion vector predictor; and coding a motionvector used for performing inter predictive coding on the current block,using one of the second motion vector predictor candidates, wherein whenthe first flag indicates that the temporal motion vector prediction isnot used, the first parameter is not coded.

With this, in the moving picture coding method, the first parameterwhich is not necessary is not coded when the temporal motion vectorprediction is not used. With this, the moving picture coding method canimprove the coding efficiency.

For example, the first parameter may include a parameter for specifyingthe coded picture.

For example, the first parameter may include a reference picture indexfor specifying the coded picture among a plurality of pictures indicatedby a reference picture list used for coding the current picture.

For example, the first parameter may include a flag indicating areference picture list to be used for specifying the coded picture amonga plurality of reference picture lists used for coding the currentpicture.

For example, when deriving the first or second candidate, a replacementvector replacing the temporal motion vector predictor may be included inthe first motion vector predictors or the second motion vectorpredictors.

With this, the moving picture coding method can suppress the reductionin coding efficiency.

For example, the moving picture coding method being for coding picturesbelonging to a base view and a dependent view in a multi-view video, themoving picture coding method may further include generating a disparityvector corresponding to a disparity between the base view and thedependent view, in which in deriving the first candidate, the disparityvector is included in the first motion vector predictors as thereplacement vector, when the current picture belongs to the dependentview and is at the beginning of a group of pictures (GOP).

With this, the moving picture coding method can suppress the reductionin coding efficiency.

For example, the moving picture coding method being for coding picturesbelonging to a base view and a dependent view in a multi-view video, themoving picture coding method may further include generating a disparityvector corresponding to a disparity between the base view and thedependent view, in which in deriving the second candidate, the disparityvector is included in the second motion vector predictors as thereplacement vector.

With this, the moving picture coding method can suppress the reductionin coding efficiency.

A moving picture decoding method according to an aspect of the presentdisclosure is a moving picture decoding method for decoding a currentblock to be decoded included in a current picture to be decoded by interpredictive decoding using a motion vector, the moving picture decodingmethod includes: decoding a first flag indicating whether or nottemporal motion vector prediction using a temporal motion vectorpredictor which is a motion vector of a block included in a decodedpicture different from the current picture is used; when the first flagindicates that the temporal motion vector prediction is used: decoding afirst parameter for calculating the temporal motion vector predictor;deriving, using the first parameter, a plurality of first motion vectorpredictor candidates including the temporal motion vector predictor;decoding a motion vector used for performing inter predictive decodingon the current block using one of the first motion vector predictorcandidates; when the first flag indicates that the temporal motionvector prediction is not used: deriving a plurality of second motionvector predictor candidates that do not include the temporal motionvector predictor; and decoding a motion vector used for performing interpredictive decoding on the current block, using one of the second motionvector predictor candidates, wherein when the first flag indicates thatthe temporal motion vector prediction is not used, the first parameteris not decoded.

With this, in the moving picture decoding method, the first parameterwhich is not necessary is not decoded when the temporal motion vectorprediction is not used. With this, the moving picture decoding methodcan improve the coding efficiency.

For example, the first parameter may include a parameter for specifyingthe decoded picture.

For example, the first parameter may include a reference picture indexfor specifying the decoded picture among a plurality of picturesindicated by a reference picture list used for decoding the currentpicture.

For example, the first parameter may include a flag indicating areference picture list to be used for specifying the coded picture amonga plurality of reference picture lists used for decoding the currentpicture.

For example, when deriving the first or second candidate, a replacementvector replacing the temporal motion vector predictor may be included inthe first motion vector predictors or the second motion vectorpredictors.

With this, the moving picture decoding method can suppress the reductionin coding efficiency.

For example, the moving picture decoding method being for decodingpictures belonging to a base view and a dependent view in a multi-viewvideo, the moving picture decoding method may further include generatinga disparity vector corresponding to disparity between the base view andthe dependent view, in which in deriving the first candidate, thedisparity vector may be included in the first motion vector predictorcandidates as the replacement vector, when the current picture belongsto the dependent view and is at the beginning of a group of pictures(GOP).

With this, the moving picture decoding method can suppress the reductionin coding efficiency.

For example, the moving picture decoding method being for decodingpictures belonging to a base view and a dependent view in a multi-viewvideo, the moving picture decoding method may further include generatinga disparity vector corresponding to disparity between the base view andthe dependent view, in which in deriving the second candidate, thedisparity vector is included in the second motion vector predictors asthe replacement vector.

With this, the moving picture decoding method can suppress the reductionin coding efficiency.

A moving picture coding apparatus according to an aspect of the presentdisclosure is a moving picture coding apparatus includes: a controlcircuitry; and a storage accessible to the control circuitry, in whichthe control circuitry executes coding a first flag indicating whether ornot temporal motion vector prediction using a temporal motion vectorpredictor which is a motion vector of a block included in a codedpicture different from the current picture is used; when the first flagindicates that the temporal motion vector prediction is used: coding afirst parameter for calculating the temporal motion vector predictor;deriving, using the first parameter, a plurality of first motion vectorpredictor candidates including the temporal motion vector predictor;coding a motion vector used for performing inter predictive coding onthe current block, using one of the first motion vector predictorcandidates; when the first flag indicates that the temporal motionvector prediction is not used: deriving a plurality of second motionvector predictor candidates that do not include the temporal motionvector predictor; and coding a motion vector used for performing interpredictive coding on the current block, using one of the second motionvector predictor candidates, wherein when the first flag indicates thatthe temporal motion vector prediction is not used, the first parameteris not coded.

With this, in the moving picture coding apparatus, the first parameterwhich is not necessary is not decoded when the temporal motion vectorprediction is not used. With this, the moving picture coding apparatuscan improve the coding efficiency.

A moving picture decoding apparatus according to an aspect of thepresent disclosure is a moving picture coding and decoding apparatuscomprising: a control circuitry; and a storage accessible to the controlcircuitry, the control circuitry performs: decoding a current picture tobe decoded by inter predictive decoding using the motion vector;decoding a first flag indicating whether or not temporal motion vectorprediction using a temporal motion vector predictor which is a motionvector of a block included in a decoded picture different from thecurrent picture is used; when the first flag indicates that the temporalmotion vector prediction is used: decoding a first parameter forcalculating the temporal motion vector predictor; deriving, using thefirst parameter, a plurality of first motion vector predictor candidatesincluding the temporal motion vector predictor; decoding a motion vectorused for performing inter predictive decoding on the current block,using one of the first motion vector predictor candidates; when thefirst flag indicates that the temporal motion vector prediction is notused: deriving a plurality of second motion vector predictor candidatesthat do not include the temporal motion vector predictor; and decoding amotion vector used for performing inter predictive decoding on thecurrent block, using one of the second motion vector predictorcandidates, in which when the first flag indicates that the temporalmotion vector prediction is not used, the first parameter is notdecoded.

With this, the moving picture decoding apparatus does not decode thefirst parameter which is not necessary when the temporal motion vectorprediction is not used. With this, the moving picture decoding apparatuscan improve the coding efficiency.

Furthermore, the moving picture decoding apparatus according to anaspect of the present disclosure includes the moving picture codingapparatus and the moving picture decoding apparatus.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Hereinafter, embodiments are described in detail with reference to theDrawings.

Each of the exemplary embodiments described below shows a general orspecific example. The numerical values, shapes, materials, structuralelements, the arrangement and connection of the structural elements,steps, the processing order of the steps and others shown in thefollowing exemplary embodiments are mere examples, and therefore do notlimit the present disclosure. Furthermore, among the components in thefollowing embodiments, the components not recited in an independentclaim encompassing the most generic concept shall be considered asoptional components.

Embodiment 1

FIG. 2 is a block diagram illustrating configuration of a moving picturecoding apparatus using a moving picture coding method according to theembodiment 1.

As illustrated in FIG. 2, the moving picture coding apparatus 100includes a subtractor 101, an orthogonal transform unit 102, aquantization unit 103, an inverse quantization unit 104, an inverseorthogonal transform unit 105, an adder 106, a block memory 107, a framememory 108, an intra prediction unit 109, an inter prediction unit 110,the switch 111, an inter prediction control unit 112, a picture typedetermining unit 113, a temporal motion vector predictor calculatingunit 114, a colPic memory 115, an global vector storage unit 116, aco-located information determining unit 117, and a variable lengthcoding unit 118.

The subtractor 101 obtains an input image sequence including a currentblock from outside of the apparatus, obtains a predictive block from aswitch 111, subtracts the predictive block from the current block so asto generate a differential block, and outputs the differential block tothe orthogonal transform unit 102.

The orthogonal transform unit 102 generates a transform coefficient bytransforming the differential block obtained from the subtractor 101from the image domain to the frequency domain, and outputs the generatedtransform coefficient to the quantization unit 103. The quantizationunit 103 generates a quantized coefficient by quantizing the transformcoefficient obtained from the quantization unit 103, and outputs thegenerated quantized coefficient to the inverse quantization unit 104 andthe variable length coding unit 118.

The inverse quantization unit 104 reconstructs the transform coefficientby performing inverse quantization on the quantized coefficient obtainedfrom the quantization unit 103, and outputs the reconstructed transformcoefficient to the inverse orthogonal transform unit 105. The inverseorthogonal transform unit 105 reconstructs the differential block bytransforming the restored transform coefficient obtained from theinverse quantization unit 104 from the frequency domain to an imagedomain, and outputs the reconstructed differential block to the adder106.

The adder 106 reconstructs the current block by adding the reconstructeddifferential block obtained from the inverse orthogonal transform unit105 and the predictive block obtained from the switch 111, and outputsthe reconstructed current block to the block memory 107 and the framememory 108. The block memory 107 stores the reconstructed input imagesequence on a block basis. The frame memory 108 stores the reconstructedinput image sequence on a frame basis.

The picture type determining unit 113 determines a picture type, among Ipicture, B picture, and P picture, to be used for coding the input imagesequence, and generates picture type information indicating thedetermined picture type. Subsequently, the picture type determining unit113 outputs the generated picture type information to the switch 111,the inter prediction control unit 112, the co-located informationdetermining unit 117, and the variable length coding unit 118.

The intra prediction unit 109 generates a predictive block by performingintra prediction on the current block using the reconstructed inputimage sequence on a block basis stored in the block memory 107, andoutputs the generated predictive block to the switch 111. The interprediction unit 110 generates the predictive block by performing interprediction on the current block using the reconstructed input imagesequence on a frame basis stored in the frame memory 108, and a motionvector derived by motion estimation, and outputs the generatedpredictive block to the switch 111.

The switch 111 outputs the predictive block generated by the interprediction unit 109 or the predictive block generated by the interprediction unit 110 to the subtractor 101 and the adder 106. Forexample, the switch 111 outputs a predictive block with a smaller costfor coding, among the two predictive blocks.

The co-located information determining unit 117 determines whether ornot the use of co-located block is prohibited. Subsequently, theco-located information determining unit 117 generates a co-located useprohibition flag indicating the determination result for each picture,and outputs the generated co-located use prohibition flag to thetemporal motion vector predictor calculating unit 114 and the variablelength coding unit 118. This co-located use prohibition flag is includedin a bitstream (typically a picture header or a slice header). Notethat, in the embodiment 1, the temporal motion vector predictor usingthe information of the co-located block by prohibiting the use ofco-located block by using the co-located use prohibition flag such thatthe temporal motion vector predictor is not added to the motion vectorpredictor candidate. However, it is not limited to this example. Forexample, a flag directly indicating whether or not a temporal predictivemotion using the information of co-located block(enable_temporal_mvp_flag) is prepared, and the flag may be included inthe bitstream (typically a picture header or a slice header).

Furthermore, the co-located information determining unit 117 determinesthe co-located block from either one of a block included in a picturepreceding the current picture (hereafter referred to as a forwardreference block) or a picture following the current picture (hereafterreferred to as a backward reference block) in display order. In otherwords, the forward reference block is a block included in a referencepicture specified by a reference picture list L0. The backward referenceblock is a block included in a reference picture specified by areference picture list L1. Note that, in the example in the embodiment1, the forward reference block is included in the reference picture listL0 and the backward reference block is included in the reference picturelist L1. However, it is not limited to this example. For example, as inthe case in which the reference picture list L0 includes the forwardreference block and the reference picture list L1 includes the forwardreference block, the reference block in the same direction may beincluded in both of the reference picture lists. Alternatively,reference blocks in opposite directions may be included in the tworeference picture lists.

Subsequently, the co-located information determining unit 117 generatesa co-located reference direction flag (collocated_from_I0_flag)indicating the determination result for each picture, and outputs thegenerated co-located reference direction flag to the temporal motionvector predictor calculating unit 114 and the variable length codingunit 118. This co-located reference direction flag is included in abitstream (typically a picture header or a slice header). For example,when the value of collocated_from_I0_flag is 1, the co-located block iscalculated from the reference picture list L0, and when the value ofcollocated_from_0_flag is 0, the co-located block is calculated from thereference picture list L1. Note that when a value indicating“prohibition” is set to the co-located use prohibition flag (forexample, when the value of enable_temporal_mvp_flag is 0), theco-located reference direction flag (collocated_from_I0_flag) may beomitted. The method for doing so shall be described in detail later.

Here, the co-located block is a block in a picture different from thecurrent picture including the current block, and is a block at aposition same as the current block in the picture. For example, amongthe pictures included in the reference picture list determined accordingto the value of the co-located reference direction flag, the picturehaving a value of the reference picture index the same as the value ofthe co-located reference picture index (collocated_ref_idx) is used asthe co-located picture. A block in the co-located picture at the sameposition as the current picture is used as the co-located block.

Here, the co-located reference picture index (collocated_ref_idx) is aindex value for specifying the co-located picture from the picturesincluded in the reference picture list determined according to the valueof the co-located reference direction flag. Collocated_ref_idx isincluded in the bitstream (typically the picture header or the sliceheader).

For example, when the picture corresponding to the reference pictureindex 0 in the reference picture list L1 is specified as the co-locatedpicture, the co-located information determining unit 117 sets the value0 to the co-located reference direction flag (collocated_from_I0_flag)and sets the value 0 to the co-located reference picture indexcollocated_ref_idx. Note that when a value indicating “prohibition” isset to the co-located use prohibition flag (for example, when the valueof enable_temporal_mvp_flag is 0), the co-located reference pictureindex (collocated_ref_idx) may be omitted. The method for doing so shallbe described in detail later. Furthermore, the positions of the currentblock and the co-located block in the pictures may not accuratelycoincide with each other. For example, the co-located informationdetermining unit 117 may set a (adjacent) block around the co-locatedblock of the current block in the picture different from the currentpicture may be set as the co-located block.

The temporal motion vector predictor calculating unit 114 derives,according to the value of the co-located use prohibition flag obtainedfrom the co-located information determining unit 117, the motion vectorpredictor candidates which are candidates of the motion vector predictorusing colPic information such as motion vector of the co-located blockstored in the colPic memory 115 or the global motion vector of thecolPic picture stored in the global vector storage unit.

More specifically, when the co-located prohibition flag is on(prohibited), the temporal motion vector predictor calculating unit 114adds the global motion vector read from the global vector storage unit116 (replacement vector) to the motion vector predictor candidates. Incontrast, when the co-located prohibition flag is off (allowed), thetemporal motion vector predictor calculating unit 114 adds the temporalmotion vector predictor calculated using the colPic information readfrom the colPic memory 115 to the motion vector predictor candidates.

Furthermore, the temporal motion vector predictor calculating unit 114assigns a value of the motion vector predictor to the motion vectorpredictor added as the candidate. Subsequently, the temporal motionvector predictor calculating unit 114 outputs the motion vectorpredictor added to the candidate and the motion vector predictor indexto the inter prediction control unit 112. In contrast, when theco-located block does not have a motion vector, the temporal motionvector predictor calculating unit 114 stops deriving a motion vector bythe temporal motion vector prediction or derives a vector with zeromotion as the motion vector predictor candidate. The temporal motionvector predictor calculating unit 114 outputs the global motion vectorto the variable length coding unit 118.

The inter prediction control unit 112 determines that the motion vectoris to be coded using a motion vector predictor having a smallest errorfrom the motion vector derived by the motion estimation, from among themotion vector predictor candidates. Here, the error indicates adifference value between the motion vector predictor candidate and themotion vector derived by the motion estimation, for example.

Furthermore, the inter prediction control unit 112 specifies the motionvector predictor index corresponding to the determined motion vectorpredictor for each block. Subsequently, the inter prediction controlunit 112 outputs the motion vector predictor index and the differencevalue between the motion vector and the motion vector predictor to thevariable length coding unit 118. Furthermore, the inter predictioncontrol unit 112 transfers the colPic information including the motionvector and others of the current block to the colPic memory 115. Theinter prediction control unit 112 transfers the motion vector and othersof the current block to the global vector storage unit 116.

The colPic memory 115 stores the colPic information including a motionvector and others of the current block for a motion vector predictorused for coding the next picture. The global vector storage unit 116calculates the global motion vector from the motion vectors of thecurrent blocks included in a picture, and stores the global motionvector for a motion vector predictor used for coding the next picture.

The variable length coding unit 118 generates a bitstream by performingvariable length coding on the quantized coefficient obtained from thequantization unit 103, the predictive emotion vector index obtained fromthe inter prediction control unit 112 and a difference value between themotion vector and the motion vector predictor, picture type informationobtained from the picture type determining unit 113, the co-located useprohibition flag (or enable_temporal_mvp_flag), a co-located referencedirection flag (collocated_from_I0_flag), and a co-located referencepicture index (collocated_ref_idx) obtained from the co-locatedinformation determining unit 117, and the global motion vector obtainedfrom the temporal motion vector predictor calculating unit 114.

FIG. 3 illustrates an overview of the process flow in the moving picturecoding method according to the embodiment 1.

The co-located information determining unit 117 determines theco-located information including the co-located use prohibition flag,the co-located reference direction flag, the co-located referencepicture index and others by a method that shall be described later, whenderiving the motion vector predictor candidate by temporal motion vectorprediction (S11).

Next, the temporal motion vector predictor calculating unit 114determines whether or not the co-located use prohibition flag is on(prohibited) (or the value of enable_temporal_mvp_flag is 0) (S12).Subsequently, if the determination result if true (yes in S12), thetemporal motion vector predictor calculating unit 114 reads the globalmotion vector from the global vector storage unit 116, and attaches theread global motion vector to the header information such as a pictureheader (S13).

Next, the temporal motion vector predictor calculating unit 114 adds, asa replacement vector for the temporal motion vector predictor, theglobal motion vector to the motion vector predictor candidate (S14).Furthermore, the temporal motion vector predictor calculating unit 114assigns a value of the motion vector predictor to the motion vectorpredictor added to the candidate.

In contrast, when the co-located use prohibition flag is off (no in S12)(or the value of enable_temporal_mvp_flag is 1), the temporal motionvector predictor calculating unit 114 reads colPic information includingthe reference motion vector and others of the co-located block from thecolPic memory, according to the co-located information, calculates thetemporal motion vector predictor using the reference motion vector inthe co-located block, and adds the calculated temporal motion vectorpredictor to the motion vector predictor candidates (S17). Furthermore,the temporal motion vector predictor calculating unit 114 assigns avalue of the motion vector predictor to the motion vector predictoradded to the candidate.

In general, if the value of the motion vector predictor index is small,a small amount of information is required. In contrast, if the value ofthe motion vector predictor index is large, a large amount ofinformation is necessary. Accordingly, the coding efficiency is higherwhen a smaller motion vector predictor index is assigned to a motionvector predictor having a high possibility of becoming a more accuratemotion vector.

Next, the inter prediction unit 110 generates the predictive block ofthe current block by performing inter prediction using a motion vectorderived by motion estimation. Subsequently, the subtractor 101, theorthogonal transform unit 102, the quantization unit 103, and thevariable length coding unit 118 code the current block by using thepredictive block generated by the inter prediction unit 110.

Furthermore, the inter prediction control unit 112 codes the motionvector by using a motion vector predictor which is a motion vectorpredictor candidate having a smallest error from the motion vector,among the motion vector predictor candidates. The inter predictioncontrol unit 112 calculates difference values between motion vectorpredictor candidates and the motion vector derived by the motionestimation as an error, and determines a motion vector predictorcandidate having the smallest error among the calculated errors as themotion vector predictor to be used for coding the motion vector.

Subsequently, the inter prediction control unit 112 outputs the motionvector predictor index corresponding to the selected motion vectorpredictor and the error information between the motion vector and themotion vector predictor to the variable length coding unit 118. Thevariable length coding unit 118 performs variable length coding on themotion vector predictor index and the error information obtained fromthe inter prediction control unit 112, and include the variable-lengthcoded motion vector predictor index and error information to thebitstream (S15).

Next, the inter prediction control unit 112 stores the colPicinformation including motion vector and others used for the interprediction to the colPic memory 115. In the colPic memory 115, themotion vector, the reference picture index value, and the predictiondirection of the reference picture are stored for calculating thetemporal motion vector predictor in the current block. The interprediction control unit 112 stores the motion vector and others used forthe inter prediction in the global vector storage unit 116 (S16).

FIG. 4 illustrates an example of the motion vector predictor candidates.The motion vector A (MV_A) is a motion vector of an adjacent block A onthe left of the current block. The motion vector B (MV_B) is a motionvector of an adjacent block B on the current block. The motion vector C(MV_C) is a motion vector of an adjacent block C on the upper right ofthe current block. Median(MV_A, MV_B, MV_C) represents a median value ofthe motion vectors A, B, and C. Here, the median value is derived by thefollowing equation 1 to equation 3, for example.

$\begin{matrix}{\mspace{79mu}\left\lbrack {{Math}.\mspace{14mu} 1} \right\rbrack} & \; \\{{{Median}\left( {x,y,z} \right)} = {x + y + z - {{Min}\left( {x,{{Min}\left( {y,z} \right)}} \right)} - {{Max}\left( {x,{{Max}\left( {y,z} \right)}} \right)}}} & \left( {{Expression}\mspace{14mu} 1} \right) \\{\mspace{79mu}\left\lbrack {{Math}.\mspace{14mu} 2} \right\rbrack} & \; \\{\mspace{79mu}{{{Min}\left( {x,y} \right)} = \left\{ \begin{matrix}x & \left( {x \leq y} \right) \\y & \left( {x > y} \right)\end{matrix} \right.}} & \left( {{Expression}\mspace{14mu} 2} \right) \\{\mspace{79mu}\left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack} & \; \\{\mspace{79mu}{{{Max}\left( {x,y} \right)} = \left\{ \begin{matrix}x & \left( {x \geq y} \right) \\y & \left( {x < y} \right)\end{matrix} \right.}} & \left( {{Expression}\mspace{14mu} 3} \right)\end{matrix}$

The values of the motion vector predictor indices are as follows: thevalue corresponding to Median(MV_A, MV_B, MV_C) is 0, the valuecorresponding to the motion vector A is 1, the value corresponding tothe motion vector B is 2, the value corresponding to the motion vector Cis 3, and the value corresponding to the temporal motion vectorpredictor (or a replacement vector) is 4. Note that, the method forassigning the motion vector predictor index is not limited to thisexample.

FIG. 5 illustrates an example of a code table used for the variablelength coding on the motion vector predictor index. In the exampleillustrated in FIG. 5, a code having a shorter code length is assignedin order from a smaller value of motion vector predictor index. Asdescribed above, assigning a smaller motion vector predictor index to amotion vector predictor candidate having high possibility of predictionaccuracy improves the coding efficiency.

FIG. 6 illustrates a flow for determining the motion vector predictorcandidates by the inter prediction control unit 112. By the flowillustrated in FIG. 6, the inter prediction control unit 112 determines,as the motion vector predictor to be used for coding the motion vector,the motion vector predictor candidate having the smallest error from themotion vector derived by the motion estimation. Subsequently, thevariable length coding is performed on the error information between themotion vector and the motion vector predictor and the motion vectorpredictor index indicating the determined motion vector predictor andincluded in the bitstream.

More specifically, first, the inter prediction control unit 112 resetsthe motion vector predictor candidate index mvp_idx and the minimummotion vector error (S21). Next, the inter prediction control unit 112compares the motion vector predictor candidate index mvp_idx and thenumber of predictive vector candidates (the number of records in thetable illustrated in FIG. 4) (S22).

If mvp_idx<the number of motion vector predictor candidates (yes inS22), the inter prediction control unit 112 calculates the motion vectorerror (error information) of the motion vector predictor candidatespecified among the motion vector predictor candidates by the value ofcurrent mvp_idx (S23). For example, the inter predictive control unit112 calculates the motion vector error by subtracting the motion vectorpredictor candidate having the motion vector predictor index=0 in FIG. 4from the motion vector used for coding the current block.

Next, the inter prediction control unit 112 compares the motion vectorerror calculated in step S23 and the minimum motion vector error (S24).If the motion vector error<minimum motion vector error (yes in S24), theinter prediction control unit 112 sets (overwrites) the motion vectorerror calculated in step S23 to the minimum motion vector error, andsets (overwrites) the current mvp_idx to the motion vector predictorindex (S25). In contrast, if motion vector error≧minimum motion vectorerror (no in S24), step S25 is skipped.

The inter prediction control unit 112 increments mvp_idx only by one(S26), and repeats the process (step S22 to step S26) as many times asthe number of the motion vector predictor candidates. Subsequently, withthe timing when mvp_idx=the number of motion vector predictor candidates(no in S22), the inter prediction control unit 112 outputs the value setto the minimum motion vector error and the motion vector predictor indexto the variable length coding unit 118, and ends the process in FIG. 6(S27).

FIG. 7 is a conceptual diagram illustrating reading/writing processfrom/on the colPic memory 115 and the global vector storage unit 116illustrated in FIG. 2. In FIG. 7, the motion vector mvCol1 in theprediction direction 1 and the motion vector mvCol2 in the predictiondirection 2 included in the co-located block in the co-located picturecolPic are stored in the colPic memory 115 and the global vector storageunit 116.

Here, when the current block is coded, the colPic information includingthe motion vector and others stored in the colPic memory 115 or theglobal motion vector in the global vector storage unit 116 is readaccording to the co-located use prohibition flag, and added to themotion vector predictor candidates.

The motion vector predictor candidate is used for coding the motionvector in the current block. Note that, in the embodiment 1, thedescription is made using an example in which the prediction direction 1is the forward reference and the prediction direction 2 is the backwardreference. However, the prediction direction 1 may be the backwardreference and the prediction direction 2 may be the forward reference,or both the prediction direction 1 and the prediction direction 2 may bethe forward reference or the backward reference. Note that, thefollowing is an example where the prediction direction 1 is a predictionusing the reference picture list L0 and the prediction direction 2 is aprediction using the reference picture list L1.

The global vector storage unit 116 stores the global motion vectorcalculated from the motion vectors in the current blocks composing thecurrent picture. For example, the global motion vector is an averagevalue of the motion vectors in the predictive directions when performingthe inter-predictive coding on the entire current picture. Note that, inthe embodiment 1, an example where an average value of the motionvectors in the current blocks composing the current picture as theglobal vector is described. However, it is not limited to this example.

For example, the global vector may be a median value or weighted averagevalue of the motion vectors in the current blocks composing the currentpicture when performing the inter-predictive coding. The global motionvector may be a motion vector which appears most frequently among themotion vectors when performing the inter predictive coding on thecurrent blocks composing the current picture. The global motion vectormay be a motion vector which refers to the closest picture in displayorder, among the motion vectors when performing the inter predictivecoding on the current blocks composing the current picture.

FIG. 8A illustrates the detailed process flow of step S11 in FIG. 3. Thefollowing shall describe FIG. 8A.

First, the co-located information determining unit 117 determineswhether or not the temporal motion vector prediction using theco-located block is to be performed on the current picture (S31).Subsequently, the co-located information determining unit 117 generatesthe co-located use prohibition flag indicating whether or not the use ofthe co-located block is allowed (temporal motion vector prediction) (orenable_temporal_mvp_flag) for each picture, and outputs the generatedco-located use prohibition flag to the variable length coding unit 118.

For example, at the time of streaming distribution, in order to suppressthe propagation of decoding error due to the temporal motion vectorprediction, there is a possibility that the co-located use prohibitionflag is set to be on with a constant interval. An exemplaryimplementation is that a counter which counts the number of codedcurrent picture is prepared, and if the number of coded pictures issmaller than a threshold, the co-located use prohibition flag is set tobe off, and if the number of coded pictures is greater than or equal tothe threshold, the co-located use prohibition flag is set to be on andthe counter is reset to 0.

In addition, for a picture that could be used for reference (forexample, P-picture and B-picture referred to by another picture), theco-located use prohibition flag is set to be on, and for a picture thatcould not be used for reference (for example, B-picture not referred toby another picture), the co-located use prohibition flag is turned offso as to suppress the decoding error from propagating, for example. Asdescribed above, by setting the co-located use prohibition flag for thepicture referred to by another picture to be on, it is possible toeffectively suppress the decoding error from propagating.

Next, the co-located information determining unit 117 determines eitherthe forward reference block or the backward reference block as theco-located block (S32). For example, the co-located informationdetermining unit 117 selects, as the co-located block, a co-locatedblock included in a picture closer to the current picture in displayorder among the co-located block (forward reference block) included inthe forward reference picture and the co-located block (backwardreference block) included in the backward reference picture.Subsequently, the co-located information determining unit 117 generates,for each picture (or slice), a co-located reference direction flagindicating whether the co-located block is the forward reference blockor the backward reference block, and the co-located reference pictureindex for specifying the co-located picture, and outputs the generatedco-located reference direction flag and the co-located reference pictureindex to the variable length coding unit 118.

FIG. 8B illustrates an example of B-picture referred to by the otherpictures. In the example in FIG. 8B, a reference structure havingmultiple layers is defined. The first picture in the stream is set to bean I-picture, and the other pictures excluding the first I-picture areset to be B-pictures. Furthermore, the picture belonging to a layer in ahigher level among the layers refers to pictures in the same level orpictures belonging to a lower level than the layer.

For example, in FIG. 8B, the picture B1 belonging to the layer 3 refersto a picture I0 belonging to the layer 0 and a picture Br2 belonging tothe layer 2. Furthermore, Br8 belonging to the layer 0, the lowestlevel, refers to the picture I0 belonging to the same layer. Here, thepictures belonging to the layer 0, the lowest level, refers only topictures preceding in display order. In this reference structure, theco-located use prohibition flag may be turned on for a picture belongingto the layer 0, highly likely to be referred to by the other pictures.

FIG. 9 illustrates the detailed process flow of step S17 in FIG. 3. Thefollowing shall describe FIG. 9.

First, the temporal motion vector predictor calculating unit 114 readscolPic information including the reference motion vector in theprediction direction 1 and the reference motion vector in the predictiondirection 2 from the colPic memory 115 (S41). Next, the temporal motionvector predictor calculating unit 114 determines whether or not theco-located block included in the colPic information has two or moremotion vectors (S42). More specifically, the temporal motion vectorpredictor calculating unit 114 determines whether or not the co-locatedblock includes the forward reference motion vector (mvL0) and thebackward reference motion vector (mvL1).

When it is determined that the co-located block includes two or moremotion vectors (yes in S42), the temporal motion vector predictorcalculating unit 114 determines whether or not the co-locate block isthe backward reference block (S43). Stated differently, the temporalmotion vector predictor calculating unit 114 determines whether or notthe picture including the co-located block is located after the currentpicture in display order.

Next, when it is determined that the co-located block is the backwardreference block (yes in S43), the temporal motion vector predictorcalculating unit 114 derives a temporal motion vector predictor bytemporal motion vector prediction using a forward reference motionvector (motion vector mvL0 for a reference picture in the referencepicture list L0) in the co-located block (S44). Subsequently, thetemporal motion vector predictor calculating unit 114 adds the temporalmotion vector predictor calculated in step S44 to the motion vectorpredictor candidates (S45).

In contrast, if the co-located block is determined to be the forwardreference block (no in S43), the temporal motion vector predictorcalculating unit 114 derives the temporal motion vector predictor by thetemporal motion vector prediction using the backward reference motionvector in the co-located block (motion vector mvL1 for the referencepicture in the reference picture list L1) (S46), and adds the derivedtemporal motion vector predictor to the motion vector predictorcandidate (S45).

In contrast, if it is determined that the co-located block includeseither one of the forward reference motion vector and the backwardreference motion vector (no in S42), the temporal motion vectorpredictor calculating unit 114 determines whether or not the co-locatedblock includes the forward reference motion vector (S47). If it isdetermined that the co-located block includes the forward referencemotion vector (yes in S47), the temporal motion vector predictorcalculating unit 114 derives a temporal motion vector predictor of thecurrent block using the forward reference motion vector of theco-located block (S48), and adds the derived temporal motion vectorpredictor to the motion vector predictor candidates (S45).

In contrast, if it is determined that the co-located block does notinclude the forward reference motion vector (no in S47), the temporalmotion vector predictor calculating unit 114 determines whether or notthe co-located block includes the backward reference motion vector(S49). If it is determined that the co-located block includes thebackward reference motion vector (yes in S49), the temporal motionvector predictor calculating unit 114 derives a temporal motion vectorpredictor of the current block using the backward reference motionvector (S50), and adds the derived temporal motion vector predictor tothe motion vector predictor candidates (S45).

In contrast, if it is determined that the co-located block does notinclude the backward reference motion vector (no in S49), the temporalmotion vector predictor calculating unit 114 ends the process in FIG. 9without adding the temporal motion vector predictor to the motion vectorpredictor candidates (S51). Alternatively, the temporal motion vectorpredictor calculating unit 114 may add a motion vector having a motionamount of 0 to the motion vector predictor candidates as the temporalmotion vector predictor in the co-located block, instead of the processin step S51.

Note that, in the process flow in FIG. 9, the temporal motion vectorpredictor calculating unit 114 determines whether or not the co-locatedblock has the forward reference motion vector in step S47, anddetermines whether or not the co-located block includes a backwardreference motion vector in step S49. However, it is not limited to thisflow. For example, the temporal motion vector predictor calculating unit114 may determine whether or not the co-located block includes thebackward reference motion vector first, and subsequently determinewhether or not the co-located block includes the forward referencemotion vector.

FIG. 10 illustrates the detailed process flow of step S13 and step S14in FIG. 3. The following shall describe FIG. 10.

First, the temporal motion vector predictor calculating unit 114 readsthe global motion vector information including at least one of theglobal motion vector in the prediction direction 1 and the global motionvector in the prediction direction 2 from the global vector storage unit116 (S61). Next, the temporal motion vector predictor calculating unit114 determines whether or not the global motion vector informationincludes two or more motion vectors (S62). More specifically, thetemporal motion vector predictor calculating unit 114 determines whetheror not the forward reference motion vector (mvL0) and the backwardreference motion vector (mvL1) are included in the global motion vectorinformation.

When it is determined that the global motion vector information includestwo or more motion vectors (yes in S62), the temporal motion vectorpredictor calculating unit 114 determines whether or not the co-locatedreference direction is the backward reference block (S63). When it isdetermined that the co-located reference direction is the backwardreference block (yes in S63), the temporal motion vector predictorcalculating unit 114 selects the forward reference motion vectorincluded in the global motion vector information (S64).

Subsequently, the temporal motion vector predictor calculating unit 114adds the selected global motion vector to the header information such asthe picture header (output to the variable length coding unit 118) andadds the selected global motion vector to the motion vector predictorcandidates in the current block (S65). Note that, the temporal motionvector predictor calculating unit 114 adds information for specifying areference picture referred to by the selected global vector (morespecifically, referred to by motion vectors used for calculating theglobal motion vector) to the header information. This information isused for the scaling that shall be described later with reference toFIG. 11A to FIG. 12B.

When it is determined that the co-located reference direction is theforward reference block (no in S63), the temporal motion vectorpredictor calculating unit 114 selects the backward reference motionvector included in the global motion vector information (S66).Subsequently, the temporal motion vector predictor calculating unit 114attaches the selected global motion vector to the header informationsuch as the picture header and adds the selected global motion vector tothe motion vector predictor candidates in the current block (S65).

Furthermore, when it is determined that the global motion vectorinformation includes either one of the forward reference motion vectorand the backward reference motion vector (no in S62), the temporalmotion vector predictor calculating unit 114 determines whether or notthe global motion vector information includes the forward referencemotion vector (S67).

When it is determined that the global motion vector information includesthe forward reference vector (yes in S67), the temporal motion vectorpredictor calculating unit 114 selects the forward reference motionvector included in the global motion vector information (S68).Subsequently, the temporal motion vector predictor calculating unit 114adds the selected global motion vector to the header information such asthe picture header and adds the selected global motion vector to themotion vector predictor candidates in the current block (S65).

In contrast, when it is determined that the global motion vectorinformation does not include the forward reference motion vector (no inS67), the temporal motion vector predictor calculating unit 114determines whether or not the global motion vector information includesthe backward reference motion vector (S69). When it is determined thatthe global motion vector information includes the backward referencevector (yes in S69), the temporal motion vector predictor calculatingunit 114 selects the backward reference motion vector included in theglobal motion vector information (S70). Subsequently, the temporalmotion vector predictor calculating unit 114 adds the selected globalmotion vector to the header information such as the picture header andadds the selected global motion vector to the motion vector predictorcandidates in the current block (S65).

In contrast, when it is determined that the global motion vectorinformation does not include the backward reference motion vector (no inS69), the temporal motion vector predictor calculating unit 114 does notadd the temporal motion vector predictor to the motion vector predictorcandidate, or sets the global motion vector to 0 (S71). Subsequently,the temporal motion vector predictor calculating unit 114 attaches theset global motion vector to the header information such as the pictureheader and adds the set global motion vector to the motion vectorpredictor candidates in the current block (S65).

Note that, in the process flow in FIG. 10, the temporal motion vectorpredictor calculating unit 114 determines whether or not the globalmotion vector includes the forward reference motion vector in step S67,and determines whether or not the global motion vector includes abackward reference motion vector in step S69. However, it is not limitedto this flow. For example, the temporal motion vector predictorcalculating unit 114 may first determine whether or not the globalmotion vector includes the backward reference motion vector, andsubsequently determines whether or not the global motion vector includesthe forward reference motion vector.

In step S63 to step S66 in FIG. 10, an example in which the temporalmotion vector predictor calculating unit 114 selects either one of theglobal motion vector mvL0 or mvL1, based on the co-located referencedirection flag. However, it is not limited to this example. For example,the temporal motion vector predictor calculating unit 114 may select theglobal motion vector mvL0 as a candidate for the motion vector predictorin the reference picture list L0, and may select the global motionvector mvL1 as a candidate for the motion vector predictor in thereference picture list L1. With this, when the global motion vector isused, it is not necessary to attach the co-located reference directionflag to the header, further improving the coding efficiency.

Next, a scaling method when the temporal motion vector predictor isadded to the motion vector predictor candidate shall be described indetail. Note that, the description for the scaling method when theglobal motion vector is added to the motion vector predictor candidateshall be omitted since the scaling methods are identical except forusing the input of the global motion vector instead of the motion vectorof the co-located block.

FIG. 11A illustrates a method for deriving the motion vector predictorcandidate (temporal motion vector predictor) by the temporal motionvector prediction using the forward reference motion vector when theco-located block is the backward reference block and the forwardreference motion vector and the backward reference motion vector areincluded. More specifically, the motion vector predictor candidate(Temporal MV) is derived by the following equation 4, using the forwardreference motion vector.TemporalMV=mvL0×(B2−B0)/(B4−B0)  (Expression 4)

Here, (B2−B0) represents time difference information between displaytimes of the picture B2 and the picture B0. Similarly, (B4−B0)represents time difference information between display times of thepicture B4 and the picture B0.

FIG. 11B illustrates a method for deriving the motion vector predictorcandidate (temporal motion vector predictor) by the temporal motionvector prediction using the backward reference motion vector. Morespecifically, the motion vector predictor candidate is derived by thefollowing equation 5, using the backward reference motion vector.TemporalMV=mvL1×(B2−B0)/(B4−B8)  (Expression 5)

FIG. 12A illustrates a method for deriving the motion vector predictorcandidate (temporal motion vector predictor) by the temporal motionvector prediction using the backward reference motion vector when theco-located block is the forward reference block and the forwardreference motion vector and the backward reference motion vector areincluded. More specifically, the motion vector predictor candidate isderived by the following equation 6, using the backward reference motionvector.TemporalMV=mvL1×(B6−B8)/(B4−B8)  (Expression 6)

FIG. 12B illustrates a method for deriving the motion vector predictorcandidate (temporal motion vector predictor) by the temporal motionvector prediction using the forward reference motion vector. Morespecifically, the motion vector predictor candidate is derived by thefollowing equation 7, using the backward reference motion vector.TemporalMV=mvL0×(B6−B8)/(B4−B0)  (Expression 7)

As described above, in the embodiment 1, the moving picture codingapparatus 100 sets the temporal motion vector prediction using a motionvector for each unit of coding in the reference picture to be off at aconstant interval, attaches a motion vector of the entire referencepicture to the header information instead, and codes the motion vectorof the current picture using the scaled global motion vector. With this,it is possible to prevent the decoding error from being propagated whilesuppressing the reduction in coding efficiency.

More specifically, when the co-located use prohibition flag is on, themoving picture coding apparatus 100 adds the global vector read from theglobal vector storage unit 116 to the motion vector predictor candidatein the current block and attaches to the header information such as thepicture header. With this, even if the reference picture is lost at thetime of decoding, the moving picture decoding apparatus can decode thebitstream without a decoding error. The error propagation is suppressedaccordingly.

Furthermore, when the co-located use prohibition flag is off, the movingpicture coding apparatus 100 can select a motion vector predictor mostsuitable for the current block according to the co-located referencedirection flag, and thus is capable of improving the compressionefficiency. In particular, the moving picture coding apparatus 100 canreduce the prediction error by using the backward reference motionvector when the co-located block is the forward reference block. Thebackward reference motion vector is a motion vector pointing a referencepicture in a direction of picture including the current block from thepicture including the co-located block, and has high possibility ofbeing close to the most suitable motion vector. Accordingly, theprediction error is small.

In contrast, the forward reference motion vector is a motion vector in adirection opposite to the direction in which the picture including thecurrent block is located, and has low possibility of being close to themost suitable motion vector. Accordingly, the prediction error is large.In the same manner, when the co-located block is the backward referenceblock, there is a high possibility that the forward reference motionvector is close to the most suitable motion vector. Accordingly, theprediction error is small.

Note that, in the embodiment 1, if the co-located block includes two ormore motion vectors, the moving picture coding apparatus 100 switchesthe co-located block used for calculating the temporal motion vectorpredictor in the current block depending on whether the co-located blockis the backward reference block or the forward reference block, it isnot limited to this example.

For example, the moving picture coding apparatus 100 may calculate thetemporal motion vector predictor using a motion vector referring to areference picture temporally close to the picture including theco-located block (a motion vector having a short temporal distance).Here, the temporal distance is determined according to the number ofpictures between the picture including the co-located block and thereference picture referred to by the co-located block in display order,for example.

Note that, in the embodiment 1, if the co-located block includes two ormore motion vectors, the moving picture coding apparatus 100 switchesthe motion vector in the co-located block used for calculating thetemporal motion vector predictor in the current block depending onwhether the co-located block is the backward reference block or theforward reference block. However, it is not limited to this example. Forexample, the moving picture coding apparatus 100 may calculate thetemporal motion vector predictor using a smaller motion vector in sizeamong the two motion vectors in the co-located block. Here, the size ofthe motion vector is indicated by an absolute value of the motionvector, for example.

Furthermore, in the embodiment 1, when the co-located use prohibitionflag is on, the moving picture coding apparatus 100 adds the globalvector read from the global vector storage unit 116 to the motion vectorpredictor candidates as a vector replacing the temporal motion vectorpredictor. However, it is not limited to this example. For example, themoving picture coding apparatus 100 may always add, as the global motionvector, the motion vector having a value of 0 to the motion vectorpredictor candidate (that is, add a vector having a movement amount of 0to the motion vector predictor candidates as the replacement vector). Inthis case, the moving picture coding apparatus 100 may attach the globalmotion vector to the header information and others. Furthermore, whenthe co-located use prohibition flag is on, the moving picture codingapparatus 100 does not have to always add the temporal motion vectorpredictor to the motion vector predictor candidates. By not adding thetemporal motion vector predictor to the motion vector predictorcandidate, it is possible to improve the coding efficiency.

Furthermore, in the embodiment 1, the moving picture coding apparatus100 adds a co-located use prohibition flag to all of the pictures.However, the co-located use prohibition flag may be added only to aspecific picture. For example, the moving picture coding apparatus 100adds the co-located use prohibition flag only to pictures referred to bythe other pictures (P-picture, B-picture referred to by the otherpictures, and a picture belonging to the lowest level in the referencestructure having more than one layer), and does not add a co-located useprohibition flag to a picture not referred to by the other pictures. Asdescribed above, the moving picture coding apparatus 100 can suppressthe decoding error from being propagated while improving the codingefficiency by attaching the co-located use prohibition flags only to thespecific pictures.

Furthermore, in the embodiment 1, the moving picture coding apparatus100 attaches the co-located use prohibition flag for each picture.However, the moving picture coding apparatus 100 may attach theco-located use prohibition flag for each slice composed of blocks.Attaching the co-located use prohibition flag for each slice improvesthe accuracy in estimating the global vector.

In the embodiment 1, the moving picture coding apparatus 100 attachesthe co-located use prohibition flag to all of the pictures. However, themoving picture coding apparatus 100 may determine that the temporalmotion vector predictor may not be added to the predictive emotionvector candidates based on the picture type, without attaching theco-located use prohibition flag. For example, in a picture referred toby the other pictures (P-picture, B-picture referred to by the otherpictures, and a picture belonging to a layer in the lowest level in thereference structure having more than one layer), the moving picturecoding apparatus 100 may add the global vector to the motion vectorpredictor candidate without adding the temporal motion vector predictorto the motion vector predictor candidates. As described above,determining whether or not the temporal motion vector predictor is addedto the motion vector predictor candidates based on the picture typeallows omitting the co-located use prohibition flag. Accordingly, it ispossible to improve the coding efficiency.

Furthermore, when the temporal motion vector predictor is not includedin the motion vector predictor candidate, the moving picture codingapparatus 100 can generate a bitstream with improved coding efficiencyby not including an unnecessary flag to the bitstream. A specificexample shall be described with reference to FIG. 13. FIG. 13 is adetailed flow of S11 in FIG. 3, and illustrates a variation of flow fordetermining the co-located information.

First, the moving picture coding apparatus 100 determines the value ofthe co-located use prohibition flag in the same method as in FIG. 8A,and codes the co-located prohibition flag representing the determinedvalue (S101). Note that, here, an example in which a flag indicatingwhether or not a temporal predictive emotion vector using theinformation of the co-located block is allowed(enable_temporal_mvp_flag) is used as the co-located use prohibitionflag shall be described.

Next, the moving picture coding apparatus 100 determines whether or notenable_temporal_mvp_flag is 1 (S102). If enable_temporal_mvp_flag is 1(yes in S102), the moving picture coding apparatus 100 determines avalue of the co-located reference direction flag and the co-locatedreference picture index in the same manner as the method in S32 in FIG.8A, and codes the co-located reference direction flag and the co-locatedreference picture index (S103 and S104).

In contrast, if enable_temporal_mvp_flag is 0 (no in S102), the movingpicture coding apparatus 100 does not code the co-located referencedirection flag and the co-located reference picture index. As describedabove, when the temporal motion vector predictor is not included in thetemporal motion vector candidates (when enable_temporal_mvp_flag is 0),the moving picture coding apparatus 100 does not attach the unnecessaryco-located reference direction flag and the co-located reference pictureindex to the bitstream. With this, the moving picture coding apparatus100 can improve the coding efficiency.

As described above, the moving picture coding apparatus 100 performs themoving picture coding process illustrated in FIG. 14.

The moving picture coding apparatus 100 performs inter-predictive codingusing a motion vector on the current block included in the currentpicture.

First, the moving picture coding apparatus 100 generates the first flag(co-located use prohibition flag) indicating whether or not the temporalmotion vector prediction using the temporal motion vector predictorwhich is a motion vector of a block included in a coded picturedifferent from the current picture (whether the temporal motion vectorprediction is allowed or prohibited) is used, and codes the generatedfirst flag (S111). The moving picture coding apparatus 100 attaches thecoded first flag to the bitstream.

Next, the moving picture coding apparatus 100 determines whether or notthe first flag indicates that the temporal motion vector prediction isused (allowed) (S112).

If the first flag indicates that the temporal motion vector predictionis used (allowed) (yes in S112), the moving picture coding apparatus 100generates the first parameter for calculating the temporal motion vectorpredictor, and codes the generated first parameter (S113). The movingpicture coding apparatus 100 attaches the coded first parameter to thebitstream.

More specifically, the first parameter includes a parameter forspecifying the coded picture (co-located picture) which is a target forreferring to the motion vector. More specifically, the first parameterincludes a reference picture index (collocated_ref_idx) for specifyingthe coded picture (co-located picture) among the pictures in thereference picture list used for coding the current picture. Furthermore,the first parameter includes a flag (collocated_from_I0_flag) indicatinga reference picture list to be used for specifying the coded picture(co-located picture) among the picture lists used for coding the currentpicture.

Here, each of the reference pictures lists list more than one referencepicture (coded picture). Furthermore, in each of the reference picturelists, the reference pictures are indicated by the reference pictureindices. The moving picture coding apparatus 100 selects a referencepicture list indicated by the flag (collcated_from_I0_flag) from amongthe reference picture lists, and identifies a picture including thereference picture index (collocated_ref_idx) from among the referencepictures included in the selected reference picture list as the codedpicture (co-located picture).

Next, the moving picture coding apparatus 100 generates a temporalmotion vector predictor using the first parameter, and derives firstmotion vector predictor candidates including the generated temporalmotion vector predictor (S114).

Next, the moving picture coding apparatus 100 codes a motion vector tobe used for performing inter-predictive coding on the current blockusing one of the first motion vector predictor candidates (S115). Morespecifically, the moving picture coding apparatus 100 selects the firstmotion vector predictor candidate having the smallest difference fromthe motion vector used for inter-predictive coding on the current blockamong the first motion vector predictor candidates, and codes the motionvector using the selected first motion vector predictor. Morespecifically, the moving picture coding apparatus 100 codes thedifference between the selected first motion vector predictor candidateand the motion vector.

Furthermore, the moving picture coding apparatus 100 codes the currentblock by the inter coding using the motion vector. Subsequently, themoving picture coding apparatus 100 attaches the coded motion vector(difference) and the coded current block to the bitstream.

In contrast, if the first flag indicates that the temporal motion vectorprediction is not used (prohibited) (no in S112), the moving picturecoding apparatus 100 does not code the first parameter (S116). Stateddifferently, the moving picture coding apparatus 100 does not generatethe first flag. The moving picture coding apparatus 100 does not attachthe first flag to the bitstream.

In addition, the moving picture coding apparatus 100 derives secondmotion vector predictors that do not include the temporal motion vectorpredictor (S117).

Next, the moving picture coding apparatus 100 codes a motion vector tobe used for performing inter-predictive coding on the current blockusing one of the second motion vector predictor candidates (S118). Notethat, a specific example of this process is identical to the process inwhich the first motion vector predictor candidates in step S115 isreplaced with the second motion vector predictor candidates.

Note that, the step S111 is performed by the flag coding unit includedin the moving picture coding apparatus 100. Furthermore, steps S113 andS116 are performed by the parameter coding unit included in the movingpicture coding apparatus 100. Steps S114 and S117 are performed by thecandidate deriving unit included in the moving picture coding apparatus100. Steps S115 and S118 are performed by the motion vector coding unitincluded in the moving picture coding apparatus 100.

Here, the function of the flag coding unit is implemented by theco-located information determining unit 117 and the variable lengthcoding unit 118 illustrated in FIG. 2, for example. Furthermore, thefunction of the parameter coding unit is implemented by the co-locatedinformation determining unit 117 and the variable length coding unit 118illustrated in FIG. 2, for example. The function of the candidatederiving unit is implemented by the inter prediction control unit 112and the temporal motion vector predictor calculating unit 114illustrated in FIG. 2. The function of the motion vector coding unit isimplemented by the subtractor 101, the inter prediction unit 110, theinter prediction control unit 112, and the variable length coding unit118 and others illustrated in FIG. 2.

In addition, the first flag (co-located use prohibition flag) and thefirst parameter (collocated_from_I0_flag and collocated_ref_idx) aregenerated and coded for each picture or slice. Stated differently, thefirst flag and the first parameter are included in a picture header of aslice header of the bitstream. Note that, the first flag and the firstparameter may be generated for different units (picture or slice). Forexample, the first flag may be generated per picture, and the firstparameter may be generated per slice.

Furthermore, at least one of the first flag and the first parameter maybe generated and coded for a plurality of pictures. Stated differently,at least one of the first flag and the first parameter may be includedin the PPS (picture parameter set) or SPS (sequence parameter set) ofthe bitstream.

Furthermore, the first flag may be included in hierarchy in multipleunits among the units in slice, picture, and pictures (sequence). Forexample, the moving picture coding apparatus 100 generates the firstflag indicating whether or not temporal motion vector prediction is usedfor the picture for each picture. Furthermore, if the first flagindicates that the temporal motion vector prediction is used, the movingpicture coding apparatus 100 generates a second flag indicating whetheror not the temporal motion vector prediction is used, for each slice inthe picture. In contrast, if the first flag indicates that the temporalmotion vector prediction is not used, the moving picture codingapparatus 100 does not generate the second flag for each slice. Notethat, the moving picture coding apparatus 100 may generate the secondflag for each slice included in the picture, only when the first flagindicates that the temporal motion vector prediction is not used.Furthermore, the moving picture coding apparatus 100 may generate thefirst flag for each picture and the second flag for each picture orslice.

Embodiment 2

In the embodiment 2, a moving picture decoding apparatus 200 whichdecodes a bitstream generated by the moving picture coding apparatus100.

FIG. 15 is a block diagram illustrating a configuration of the movingpicture decoding apparatus 200 using a moving picture decoding methodaccording to the embodiment 2.

In the embodiment 2, a block included in a picture preceding a currentpicture to be decoded (a reference picture specified by the referencepicture list L0) in display order is referred to as a forward referenceblock. Furthermore, a block included in a picture following the currentpicture (a reference picture specified by the reference picture list L1)in display order is referred to as a backward reference block.

As illustrated in FIG. 15, the moving picture decoding apparatus 200includes a variable length decoding unit 201, an inverse quantizationunit 202, an inverse orthogonal transform unit 203, an adder 204, ablock memory 205, a frame memory 206, an intra prediction unit 207, aninter prediction unit 208, a switch 209, an inter prediction controlunit 210, a temporal motion vector predictor calculating unit 211, and acolPic memory 212.

The variable length decoding unit 201 performs variable length decodingon the input bitstream, and obtains picture type information, a motionvector predictor index, a co-located use prohibition flag (orenable_temporal_mvp_flag), a co-located reference direction flag(collocated_from_I0_flag), a co-located reference picture index(collocated_ref_idx), a global motion vector, and a quantizationcoefficient. The variable length decoding unit 201 outputs (i) thepicture type information to the switch 209 and the inter predictioncontrol unit 210, (ii) the motion vector predictor index to the interprediction control unit 210, (iii) a co-located use prohibition flag (orenable_temporal_mvp_flag), a co-located reference direction flag(collocated_from_I0_flag), a co-located reference picture index(collocated_ref_idx), and the global motion vector to the temporalmotion vector predictor calculating unit 211, and (iv) quantizationcoefficient to the inverse quantization unit 202.

The inverse quantization unit 202 reconstructs a transform coefficientby inversely quantizing the quantization coefficient obtained from thevariable length decoding unit 201, and outputs the reconstructedtransform coefficient to the inverse orthogonal transform unit 203. Theinverse orthogonal transform unit 203 reconstructs the differentialblock by transforming the restored transform coefficient obtained fromthe inverse quantization unit 202 from the frequency domain to an imagedomain, and outputs the reconstructed differential block to the adder204.

The adder 204 reconstructs a differential block reconstructed by addinga differential block obtained from the inverse orthogonal transform unit203 and a predictive block obtained from the switch 209. Subsequently,the adder 204 outputs a decoded image sequence including thereconstructed decoded block to outside of the apparatus and stores thedecoded image sequence in the block memory 205 and the frame memory 206.

The block memory 205 stores a decoded image sequence obtained from theadder 204 on a block basis. The frame memory 206 stores a decoded imagesequence obtained from the adder 204 on a frame basis.

The intra prediction unit 207 generates a predictive block of thecurrent block by performing intra-prediction using a decoded imagesequence per block stored in the block memory 205, and outputs thegenerated predictive block to the switch 209. The inter prediction unit208 generates a predictive block of the current block by performinginter prediction using a decoded image sequence per frame stored in theframe memory 206, and outputs the generated predictive block to theswitch 209. The switch 209 outputs the predictive block generated by theintra prediction unit 207 or the predictive block generated by the interprediction unit 208 to the adder 204.

When the co-located use prohibition flag obtained from the variablelength decoding unit 201 is off, the temporal motion vector predictorcalculating unit 211 derives a motion vector predictor candidate(temporal motion vector predictor) using colPic information such as amotion vector of the co-located block stored in the colPic memory 212.In contrast, when the co-located use prohibition flag is on, thetemporal motion vector predictor calculating unit 211 adds the globalmotion vector obtained from the variable length decoding unit 201 to themotion vector predictor candidate.

Furthermore, the temporal motion vector predictor calculating unit 211assigns a motion vector predictor index to the motion vector predictoradded as the candidate. Subsequently, the temporal motion vectorpredictor calculating unit 211 outputs the motion vector predictor andthe motion vector predictor index to the inter predictive control unit210.

Furthermore, when the co-located block does not have a motion vector,the temporal motion vector predictor calculating unit 211 may stopderiving a motion vector by the temporal motion vector prediction or adda motion vector having motion amount 0 to the motion vector predictorcandidate.

The inter prediction control unit 210 specifies a motion vectorpredictor corresponding to a motion vector predictor index obtained fromthe variable length decoding unit 201 among the motion vector predictorcandidates. Subsequently, the inter prediction control unit 210calculates a motion vector used for inter prediction by adding errorinformation between the motion vector and motion vector predictor to thespecified motion vector predictor. Furthermore, the inter predictioncontrol unit 210 stores the colPic information including the motionvector and others of the current block in the colPic memory 212.

FIG. 16 is a diagram illustrating an overview of process flow of amoving picture decoding method according to the embodiment 2.

First, the variable length decoding unit 201 decodes a co-located useprohibition flag on a picture basis (S81). The variable length decodingunit 201 subsequently determines whether or not the co-located useprohibition flag is off (S82). When the co-located use prohibition flagis off (yes in S82), the variable length decoding unit 201 decodes theco-located reference direction flag and the co-located reference pictureindex (collocated_ref_idx) on a picture basis (S83). The variable lengthdecoding unit 201 outputs the decoded co-located use prohibition flag,the co-located reference direction flag, and the co-located referencepicture index to the temporal motion vector predictor calculating unit211.

Next, the temporal motion vector predictor calculating unit 211 readsthe colPic information including the reference motion vector and othersin the co-located block from the colPic memory 212 according to theco-located information, generates the temporal motion vector predictorusing the reference motion vector in the co-located block, and adds thegenerated temporal motion vector predictor to the motion vectorpredictor candidate, in the same manner as FIG. 9 (S84).

In contrast, when the co-located use prohibition flag is on (no in S82),the temporal motion vector predictor calculating unit 211 obtains theglobal motion vector stored in the header information such as pictureheader from the variable length decoding unit 201, and adds the obtainedglobal motion vector to the motion vector predictor candidate (S87).

Next, the inter prediction control unit 210 selects a motion vectorpredictor corresponding to the decoded motion vector predictor index,out of the motion vector predictor candidates (S85). Furthermore, theinter prediction control unit 210 derives a motion vector by adding thepredictive error information to the selected motion vector predictor,and outputs the derived motion vector to the inter prediction unit 208.Subsequently, the inter prediction unit 208 generates a predictive blockof the current block by inter prediction using the derived motionvector.

Next, the inter prediction control unit 210 stores the colPicinformation including the motion vector and others used for the interprediction in the colPic memory 212 (S86). In the colPic memory 212, themotion vector, the reference picture index value, and the predictiondirection of the reference picture are stored for calculating thetemporal motion vector predictor of the current block.

Note that, a method for selecting the reference motion vector forcalculating the temporal motion vector predictor when the referenceblock includes two or more reference motion vectors is not limited to amethod based on the co-located block reference direction flag. Forexample, the moving picture decoding apparatus 200 may calculate atemporal distance of the reference motion vector, and may use atemporally shorter reference motion vector. Here, the temporal distanceis calculated based on the number of pictures between the referencepicture including the reference block and a picture to be referred to bythe reference picture. Furthermore, for example, the moving picturedecoding apparatus 200 may calculate the size of the reference motionvector, and determine a motion vector derived by a reference motionvector smaller in size as a temporal motion vector predictor.

FIG. 17 is a diagram illustrating an example of syntax of a bitstream inthe moving picture decoding method according to the embodiment 2. InFIG. 17, forbid_collocated_flag represents the co-located useprohibition flag, tmv_x represents horizontal component of the globalmotion vector, tmv_y represents vertical component of the global motionvector, and collocated_from_I0_flag represents the co-located referencedirection flag.

As illustrated in FIG. 17, when the co-located use prohibition flag(forbid_collocated_flag) is 1, the global motion vector (tmv_x andtmv_y) is attached to the bitstream, and added to the motion vectorpredictor candidate.

Alternatively, when the co-located use prohibition flag(forbid_collocated_flag) is 0, the co-located reference direction flag(collocated_from_I0_flag) is attached to the bitstream. Subsequently,the co-located block is determined according to the co-located referencedirection flag, and a temporal motion vector predictor is calculatedusing a reference motion vector in the co-located block. Note that,here, collocated_from_I0_flag having a value of 1 indicates that theco-located block is a forward reference block, andcollocated_from_I0_flag having a value of 0 indicates that theco-located block is a backward reference block. However, it is notnecessarily limited to this example.

Note that, in the embodiment 2, when the co-located use prohibition flagis on, the moving picture decoding apparatus 200 uses the global motionvector decoded from the header information and others. However, theglobal motion vector having a value of 0 may always be added to themotion vector predictor candidate depending on the coding method. Inthis case, the global motion vector is not attached to the headerinformation and others, and thus the decoding process is omitted.Furthermore, when the co-located use prohibition flag is on, the movingpicture decoding apparatus 200 does not have to always add the temporalmotion vector predictor to the motion vector predictor candidates.

As described above, in the embodiments 1 and 2, the moving picturecoding apparatus 100 sets the temporal motion vector prediction using amotion vector for each coding process unit in the reference picture tobe off, and attaches the global motion vector of the reference pictureto the header information. In addition, the moving picture codingapparatus 100 can generate a bitstream which prevents the decoding errorfrom propagating while suppressing the reduction in coding efficiency bycoding the motion vector in the current picture. Furthermore, the movingpicture decoding apparatus 200 can appropriately decode the bitstreamgenerated as described above.

More specifically, when the co-located use prohibition flag is on, themoving picture coding apparatus 100 adds the global vector read from theglobal vector storage unit 116 to the motion vector predictor candidatein the current block and attaches to the header information such as thepicture header. With this, even if the reference picture is lost at thetime of decoding, the moving picture decoding apparatus 200 can decodethe bitstream without a decoding error. As described above, the movingpicture decoding apparatus 200 can appropriately decode the bitstreamwhose error propagation is suppressed.

Furthermore, when the co-located use prohibition flag is off, the movingpicture decoding apparatus 200 can appropriately decode the bitstreamincluding a current block having a most suitable motion vector predictorselected, according to the co-located reference direction flag.

Note that, in the embodiments 1 and 2, when the co-located useprohibition flag is on, the moving picture coding apparatus 100 uses theglobal vector read from the global vector storage unit 116. However, theglobal motion vector having a value of 0 may always be added to themotion vector predictor candidate. Furthermore, when the co-located useprohibition flag is on, the moving picture coding apparatus 100 does nothave to always add the temporal motion vector predictor to the motionvector predictor candidates. This configuration reduces the decodingprocess in the moving picture decoding apparatus 200.

Furthermore, in the embodiment 2, the moving picture decoding apparatus200 decodes the co-located use prohibition flag of all of the pictures.However, only the co-located use prohibition flag of a specific picturemay be decoded. For example, the moving picture decoding apparatus 200decodes only a co-located use prohibition flag for a picture referred toby another picture (P picture, B picture referred to by another picture,and a picture belonging to the lowest level in a reference structurehaving multiple layers), and does not decode a co-located useprohibition flag in a picture not referred to by another picture. Asdescribed above, by decoding only the co-located use prohibition flag ofthe specific picture, it is possible to reduce the decoding process andsuppresses the decoding error from propagating.

Furthermore, in the embodiment 2, the moving picture decoding apparatus200 decodes the co-located use prohibition flag for each picture.However, the moving picture decoding apparatus 200 may decode theco-located use prohibition flag for each slice composed of blocks.Decoding the co-located use prohibition flag for each slice improves theaccuracy in estimating the global vector.

Furthermore, in the embodiment 2, the moving picture decoding apparatus200 decodes all of the co-located use prohibition flags in all of thepictures. However, the temporal motion vector predictor may not be addedto the motion vector predictor candidate based on the picture type. Forexample, in a picture referred to by the other pictures (P-picture,B-picture referred to by the other pictures, and a picture belonging toa layer in the lowest level in the reference structure having more thanone layer), the moving picture decoding apparatus 200 may add the globalvector to the motion vector predictor candidate without adding thetemporal motion vector predictor to the motion vector predictorcandidates. As described above, by determining whether the temporalmotion vector predictor or the global motion vector is added to themotion vector predictor candidate based on the picture type allowsimprovement on the coding efficiency while reducing the decodingprocess.

Furthermore, when the temporal motion vector predictor is not includedin the motion vector predictor candidate, the moving picture codingapparatus 100 can generate a bitstream with improved coding efficiencyby not including an unnecessary flag to the bitstream. Furthermore, themoving picture decoding apparatus 200 can appropriately decode thebitstream generated as described above. A specific example shall bedescribed with reference to FIG. 18. FIG. 18 illustrates a variation offlow for decoding the co-located information.

First, the moving picture decoding apparatus 200 decodes the co-locateduse prohibition flag (S201). Note that, here, an example in which a flagindicating whether or not a temporal predictive motion vector using theinformation of the co-located block is allowed(enable_temporal_mvp_flag) is decoded shall be described.

Next, the moving picture decoding apparatus 200 determines whether ornot enable_temporal_mvp_flag is 1 (S202). When enable_temporal_mvp_flagis 1 (yes in S202), the moving picture decoding apparatus 200 decodesthe co-located reference direction flag and the co-located referencepicture index separately (S203 and S204).

In contrast, if enable_temporal_mvp_flag is 0 (no in S202), the movingpicture coding apparatus 200 does not decode the co-located referencedirection flag and the co-located reference picture index. As describedabove, when the temporal motion vector predictor is not included in thetemporal motion vector candidates (when enable_temporal_mvp_flag is 0),the moving picture coding apparatus 100 can generate a bitstream withimproved coding efficiency by not attaching the unnecessary co-locatedreference direction flag and the co-located reference picture index tothe bitstream. Furthermore, the moving picture decoding apparatus 200can appropriately decode the bitstream.

FIG. 19A and FIG. 19B illustrate examples of syntax when a co-locateduse prohibition flag (enable_temporal_mvp_flag) indicating whether ornot the temporal motion vector predictor using information of theco-located block is allowed is attached to the picture parameter set(PPS), and a co-located reference direction flag(collocated_from_I0_flag) and the co-located reference picture index(collocated_ref_idx) are attached to the slice header.

When the value of the co-located use prohibition flag is 1, calculatinga temporal motion vector predictor using the co-located information isallowed. When the value of the co-located use prohibition flag is 0,calculating a temporal motion vector predictor using the co-locatedinformation is prohibited.

When the value of the co-located reference direction flag is 1, aco-located picture is selected from the reference picture list in theprediction direction 1. When the value of the co-located referencedirection flag is 0, a co-located picture is selected from the referencepicture list in the prediction direction 1.

Among the pictures included in the reference picture list determinedaccording to the value of collocated_from_I0_flag, a picture having areference picture index collocated_ref_idx is selected as the co-locatedpicture.

Furthermore, FIG. 20 illustrates an example of syntax when all of theco-located use prohibition flag indicating whether or not the temporalmotion vector predictor using the information of the co-located block isallowed (enable_temporal_mvp_flag), the co-located reference directionflag (collocated_from_I0_flag), and the co-located reference pictureindex (collocated_ref_idx) are attached to the slice header.

As illustrated in FIG. 19B and FIG. 20, when the value ofenable_temporal_mvp_flag is 0, collocated_from_I0_flag andcollocated_ref_idx are not attached to the bitstream.

As described above, the moving picture decoding apparatus 200 performsthe moving picture decoding process illustrated in FIG. 21.

The moving picture decoding apparatus 200 performs inter predictivecoding using a motion vector on the current block in the currentpicture.

First, the moving picture decoding apparatus 200 decodes the first flag(co-located use prohibition flag) indicating whether or not temporalmotion vector prediction using the temporal motion vector predictorwhich is a motion vector of a block in a decoded picture different fromthe current picture (whether the temporal motion vector prediction isallowed or prohibited) (S211). Accordingly, the moving picture decodingapparatus 200 obtains the coded first flag from the bitstream, andobtains the first flag by decoding the coded first flag.

Next, the moving picture decoding apparatus 200 determines whether ornot the first flag indicates that the temporal motion vector predictionis used (allowed) (S212).

When the first flag indicates that the temporal motion vector predictionis used (allowed) (yes in S212), the moving image decoding apparatus 200decodes the first parameter for calculating the temporal motion vectorpredictor (S213). More specifically, the moving picture decodingapparatus 200 obtains the coded first parameter from the bitstream, andobtains the first parameter by decoding the obtained coded firstparameter. More specifically, the first parameter includes a parameterfor specifying the decoded picture (co-located picture) which is atarget referred to by the motion vector. More specifically, the firstparameter includes a reference picture index (collocated_ref_idx) forspecifying the decoded picture (co-located picture) among the picturesin the reference-picture list used for decoding the current picture. Inaddition, the first parameter includes a flag indicating a referencepicture list to be used (collocated_from_I0_flag) for specifying thecoded picture (co-located picture) among the reference picture listsused for decoding the current picture.

Next, the moving picture decoding apparatus 200 determines the temporalmotion vector predictor using the first parameter, and derives the firstmotion vector predictor candidate including the determined temporalmotion vector predictor (S214).

Next, the moving picture decoding apparatus 200 decodes a motion vectorused for performing inter predictive decoding on the current block usingone of the first motion vector predictor candidates (S215). Morespecifically, the moving picture decoding apparatus 200 obtains a codedmotion vector (difference value) from the bitstream. Subsequently, themoving picture decoding apparatus 200 generates the difference value ofthe motion vector by decoding the coded motion vector (differencevalue). Next, a motion vector is generated by using a difference valuebetween one of the first motion vector predictor candidates and themotion vector.

Furthermore, the moving picture decoding apparatus 200 decodes thecurrent block by performing inter decoding using the motion vector. Morespecifically, the moving picture decoding apparatus 200 obtains a codedcurrent block (difference value) from the bitstream. Subsequently, themoving picture decoding apparatus 200 generates a difference value ofthe current block by decoding the coded current block (differencevalue). Next, the moving picture decoding apparatus 200 reconstructs thecurrent block using a difference value between the motion vector and thecurrent block.

In contrast, when the first flag indicates that the temporal motionvector prediction is not used (prohibited) (no in S212), the movingpicture decoding apparatus 200 does not decode the first parameter(S216). Stated differently, the moving picture decoding apparatus 200does not obtain the first parameter from the bitstream.

Next, the moving picture decoding apparatus 200 derives the secondmotion vector predictor candidate that does not include the temporalmotion vector predictor (S217).

Next, the moving picture decoding apparatus 200 performs inter decodingon the current block, using one of the second motion vector predictorcandidates (S218). Note that, a specific example of the process isidentical to the process in which the first motion vector predictorcandidates in step S215 described above is replaced with the secondmotion vector predictor candidates.

Note that step S211 is performed by the flag decoding unit included inthe moving picture decoding apparatus 200. Furthermore, steps S213 andS216 are performed by a parameter decoding unit included in the movingpicture decoding apparatus 200. Steps S214 and S217 are performed by acandidate deriving unit included in the moving picture decodingapparatus 200. Steps S215 and S218 are performed by the motion vectordecoding unit included in the moving picture decoding apparatus 200.

Here, the function of the flag decoding unit is implemented by thevariable length decoding unit 201 and others illustrated in FIG. 15, forexample. Here, the function of the parameter decoding unit isimplemented by the variable length decoding unit 201 and othersillustrated in FIG. 15, for example. The function of the candidatederiving unit is implemented by the inter prediction control unit 210and the temporal motion vector predictor calculating unit 211illustrated in FIG. 15. The function of the motion vector decoding unitis implemented by the variable length decoding unit 201, the interprediction unit 208, and the inter prediction control unit 210 andothers illustrated in FIG. 15.

(Variation)

Next, a moving picture coding apparatus 300 according to a variation ofthe embodiment 1 shall be described with reference to FIG. 22. FIG. 22is a block diagram of the moving picture coding apparatus 300 accordingto the variation of the embodiment 1. Note that, the description on thepoints same as the embodiment 1 is omitted, and the description shall bemade focusing on the difference.

As illustrated in FIG. 22, the moving picture coding apparatus 300includes a first coding unit 310 which generates a base bitstream bycoding a base view, and a second coding unit 320 which generates adependent bitstream by coding a dependent view. Note that, in FIG. 22,an example in which the moving picture coding apparatus 300 outputs thebase bitstream and the dependent bitstream as independent streams.However, it is not limited to this example, and the moving picturecoding apparatus 300 may output one bitstream which includes the basebitstream and the dependent bitstream joined as one.

The basic configuration of the first coding unit 310 and the secondcoding unit 320 are identical to the moving picture coding apparatus 100illustrated in FIG. 2. However, in addition to the function as themoving picture coding apparatus 100, the second coding unit 320 hasfunction for referring to the frame memory 108 and others in the firstcoding unit 310.

Next, a moving picture coding method according to the variation of theembodiment 1 shall be described with reference to FIG. 23 and FIG. 24.FIG. 23 is a flowchart illustrating an operation of the moving picturecoding method according to the variation of the embodiment 1. FIG. 24illustrates an example of picture belonging to the base view and thedependent view.

As illustrated in FIG. 24, the base view includes pictures I11, P12,P13, P14, I15, P16, and P17. Among pictures belonging to the base view,the pictures at the beginning of group of pictures (GOP) I11 and I15 areI pictures, and the rest of the pictures P12, P13, P14, P16, and P17 areP pictures. Note that, the base view is coded and decoded referring onlyto pictures belonging to the base view (that is, intra predictive codingor inter predictive coding).

The dependent view is composed of pictures P21, P22, P23, P24, P25, P26,and P27, as illustrated in FIG. 24. All of the pictures P21, P22, P23,P24, P25, P26, and P27 belonging to the dependent view are P pictures.Note that, the dependent view is coded and decoded by referring to, inaddition to a picture belonging to the dependent view, a picturecorresponding to the picture to be processed belonging to the base view(stated differently, the inter view predictive coding).

The base view and the dependent view are video of the subject fromdifferent viewpoints. Stated differently, corresponding pictures in thebase view and the dependent view (pictures to which the same time stampis attached) have a disparity in the horizontal direction. Subsequently,the second coding unit 320 can code a picture belonging to the dependentview by using an image corresponding to the current picture belonging tothe base view as the reference picture. The following shall describe anoperation of the temporal motion vector predictor calculating unit 114in the second coding unit 320 with reference to FIG. 23.

First, the temporal motion vector predictor calculating unit 114determines whether or not the temporal motion vector predictor can beobtained when coding the current block (S91). When the temporal motionvector predictor is not obtained (yes in S91), the temporal motionvector predictor calculating unit 114 includes the disparity vector tobe described later as the motion vector predictor candidate (S92). Incontrast, when the temporal motion vector predictor can be obtained (noin S91), the temporal motion vector predictor calculating unit 114includes the temporal motion vector predictor to the motion vectorpredictor candidate (S93).

Here, the case in which the temporal motion vector predictor cannot beobtained includes a case in which the current block is the pictures P21and P25 which are at the beginning of the GOP. The pictures P21 and P25at the beginning of the GOP cannot refer to a picture preceding thepicture in display order. To put it differently, when the coding orderand the display order match, the pictures P21 and P25 can only refer tothe corresponding pictures I11 and I15 corresponding in the base view.

However, the pictures I11 and I15 are I pictures, and thus there is noinformation on motion vector. In this case, the temporal motion vectorpredictor calculating unit 114 includes the disparity vector stored inthe global vector storage unit 116 to the motion vector predictorcandidate as the replacement vector of the temporal motion vectorpredictor, and includes the disparity vector to the header informationof the dependent bitstream.

Here, the disparity vector is a vector corresponding to the disparitybetween the base view and the dependent view. More specifically, theinter predictive control unit 112 in the second coding unit 320 outputsa motion vector when performing inter-view predictive coding on theblocks composing the current picture in the dependent view (stateddifferently, the motion vector when coding is performed using acorresponding picture in the base view as the reference picture) to theglobal vector storage unit 116. Subsequently, the global vector storageunit 116 stores an average value, a median value, or a mode value of themotion vectors obtained from the inter prediction control unit 112 foreach picture as the disparity vector.

Note that, in step S92 in FIG. 23, the temporal motion vector predictorcalculating unit 114 may select a disparity vector calculated by thepicture P21 at the beginning of the GOP immediately before the GOPbelonging to the picture P25 (disparity vector having the picture I11 asthe reference picture) or a disparity vector calculated by the pictureP24 which is coded immediately before (the disparity vector having thepicture P14 as the reference picture).

Furthermore, in step S91 in FIG. 23, a specific example of a case wherethe temporal motion vector predictor cannot be obtained is not limitedto the example described above, and may be a case in which theco-located use prohibition flag in the current picture is on. Since thedescription of the co-located use prohibition flag is common to thedescription on the embodiment 1, overlapping description shall beomitted.

As described above, the present disclosure is applicable to a case inwhich the base view and the dependent view composing the multi-viewvideo are coded. More specifically, by switching whether the temporalmotion vector predictor or the disparity vector which is a replacementvector of the temporal motion vector predictor is included as a motionvector predictor candidate when coding the current picture belonging tothe dependent view allows preventing the decoding error from propagatingwhile suppressing the reduction in the coding efficiency.

Next, a moving picture coding apparatus 400 according to a variation ofthe embodiment 2 shall be described with reference to FIG. 25. FIG. 25is a block diagram of the moving picture coding apparatus 400 accordingto the variation of the embodiment 2. Note that, the description on thepoints same as the embodiment 2 is omitted, and the description shall bemade focusing on the difference.

The moving picture decoding apparatus 400 includes a first decoding unit410 which generates a base view by decoding the base bitstream, and asecond decoding unit 420 which generates a dependent view by decodingthe dependent bitstream as illustrated in FIG. 25. Note that, althoughFIG. 25 illustrates an example in which independent base bitstream andthe dependent bitstream are separately input to the moving picturedecoding apparatus 400, it is not limited to this example. For example,one bitstream in which the base bitstream and the dependent bitstreamare joined is input, and may be divided into the base bitstream and thedependent bitstream inside the moving picture decoding apparatus 400.

The basic configuration of the first decoding unit 410 and the seconddecoding unit 420 is identical to the moving picture decoding apparatus200 illustrated in FIG. 15. However, the second decoding unit 420 has afunction of referring to the frame memory 206 and others of the firstdecoding unit 410, in addition to the function of the moving picturedecoding apparatus 200. More specifically, the moving picture decodingapparatus 400 decodes the base bitstream and the dependent bitstreamcoded by the moving picture coding apparatus 300.

In addition, the second decoding unit 420 in the moving picture decodingapparatus 400 can switch whether the temporal motion vector predictorstored in the colPic memory 212 or the disparity vector included in theheader information of the dependent bitstream is included as one of themotion vector predictor candidates for the current block. Note that, theoperation of the temporal motion vector predictor calculating unit 211included in the second decoding unit 420 is identical to the process inFIG. 23.

The moving picture coding apparatus and the moving picture decodingapparatus according to the embodiment has been described above. Thepresent disclosure is not limited to the embodiment.

Each processing unit constituting the moving picture coding apparatusand the moving picture decoding apparatus is typically configured froman LSI which is an integrated circuit. The processing units may beindividually packaged in one chip, or one chip may include a part of orall of the processing units.

The form of integration is not limited to LSI, but may be a dedicatedcircuit or a general-purpose processor. In addition, it is alsoacceptable to use a Field Programmable Gate Array (FPGA) that isprogrammable after the LSI has been manufactured, and a reconfigurableprocessor in which connections and settings of circuit cells within theLSI are reconfigurable.

In each embodiment, each component may be configured of a dedicatedhardware or implemented by executing a software program suitable foreach component. Each component may be implemented by a program executingunit such as CPU or processor reading and executing a software programrecorded on such as a hard disk or a recording medium a semiconductormemory.

Stated differently, the moving picture coding apparatus and the movingpicture decoding apparatus include a control circuitry and a storageelectrically connected to (accessible from the control device) thecontrol circuitry. The control circuitry includes at least one of adedicated software and a program execution unit. Furthermore, when thecontrol circuitry includes a program execution unit, the storage storesa software program executed by the program executing unit.

Furthermore, the present disclosure may be the software program, or anon-transitory computer readable recording medium on which the programis stored. Needless to say, the program can be distributed via atransmission medium such as the Internet.

Furthermore, the numbers used in the description above are examples forspecifically describing the present disclosure. Accordingly, the presentdisclosure is not limited by the numbers presented as examples.

Furthermore, division of the functional block in the block diagram is anexample, and functional blocks may be implemented as one functionalblock, one functional block may be divided into more than one block, ora part of the function may be moved to another functional block.Alternatively, the function of the functional blocks having similarfunction may be processed concurrently or in time-division by a singlehardware or software.

The order of execution of steps including the moving picture codingmethod and the moving picture decoding method is an example forspecifically describing the present disclosure, and may be in anotherorder. Furthermore, a part of the step may be executed at the same time(concurrently) with the other steps.

Although the moving picture coding apparatus and the moving picturedecoding apparatus according to one or multiple embodiments of thepresent disclosure have been described in detail above, those skilled inthe art will readily appreciate that many modifications are possible inthe exemplary embodiments without materially departing from the novelteachings and advantages of the present invention. Accordingly, all suchmodifications are intended to be included within the scope of thepresent invention.

Embodiment 3

The processing described in each of embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofembodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image coding apparatus using theimage coding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 26 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 26, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital camera, is capable ofcapturing both still images and video. Furthermore, the cellular phoneex114 may be the one that meets any of the standards such as GlobalSystem for Mobile Communications (GSM) (registered trademark), CodeDivision Multiple Access (CDMA), Wideband-Code Division Multiple Access(W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of embodiments (i.e., the camerafunctions as the image coding apparatus according to an aspect of thepresent invention), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the coded data (i.e., functions as the imagedecoding apparatus according to an aspect of the present invention).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111; The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for encoding and decoding video may be integratedinto some type of a recording medium (such as a CD-ROM, a flexible disk,and a hard disk) that is readable by the computer ex111 and others, andthe coding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the video data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 27. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of embodiments (i.e.,data coded by the image coding apparatus according to an aspect of thepresent invention). Upon receipt of the multiplexed data, the broadcastsatellite ex202 transmits radio waves for broadcasting. Then, a home-useantenna ex204 with a satellite broadcast reception function receives theradio waves. Next, a device such as a television (receiver) ex300 and aset top box (STB) ex217 decodes the received multiplexed data, andreproduces the decoded data (i.e., functions as the image decodingapparatus according to an aspect of the present invention).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording medium ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 28 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast; a modulation/demodulation unit ex302 thatdemodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, respectively (which function as the imagecoding apparatus and the image decoding apparatus according to theaspects of the present invention); and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation. Furthermore, the television ex300 includes a control unitex310 that controls overall each constituent element of the televisionex300, and a power supply circuit unit ex311 that supplies power to eachof the elements. Other than the operation input unit ex312, theinterface unit ex317 may include: a bridge ex313 that is connected to anexternal device, such as the reader/recorder ex218; a slot unit ex314for enabling attachment of the recording medium ex216, such as an SDcard; a driver ex315 to be connected to an external recording medium,such as a hard disk; and a modem ex316 to be connected to a telephonenetwork. Here, the recording medium ex216 can electrically recordinformation using a non-volatile/volatile semiconductor memory elementfor storage. The constituent elements of the television ex300 areconnected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or encode the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orencoding.

As an example, FIG. 29 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 30 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 28. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 31A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, encoded or decodeddata of the received video, the still pictures, e-mails, or others; anda slot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 31B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of embodiments (i.e.,functions as the image coding apparatus according to the aspect of thepresent invention), and transmits the coded video data to themultiplexing/demultiplexing unit ex353. In contrast, during when thecamera unit ex365 captures video, still images, and others, the audiosignal processing unit ex354 codes audio signals collected by the audioinput unit ex356, and transmits the coded audio data to themultiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of embodiments (i.e., functions as the imagedecoding apparatus according to the aspect of the present invention),and then the display unit ex358 displays, for instance, the video andstill images included in the video file linked to the Web page via theLCD control unit ex359. Furthermore, the audio signal processing unitex354 decodes the audio signal, and the audio output unit ex357 providesthe audio.

Furthermore, similarly to the television ex300, a terminal such as thecellular phone ex114 probably have 3 types of implementationconfigurations including not only (i) a transmitting and receivingterminal including both a coding apparatus and a decoding apparatus, butalso (ii) a transmitting terminal including only a coding apparatus and(iii) a receiving terminal including only a decoding apparatus. Althoughthe digital broadcasting system ex200 receives and transmits themultiplexed data obtained by multiplexing audio data onto video data inthe description, the multiplexed data may be data obtained bymultiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofembodiments can be obtained.

Furthermore, the present invention is not limited to embodiments, andvarious modifications and revisions are possible without departing fromthe scope of the present invention.

Embodiment 4

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since towhich standard each of the plurality of the video data to be decodedconform cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG-2 Transport Stream format.

FIG. 32 illustrates a structure of the multiplexed data. As illustratedin FIG. 32, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary audio to be mixed with the primary audio.

FIG. 33 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 34 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 34 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 34, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 35 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 35. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 36 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 37. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 37, the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 38, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 39 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute informationincluded in the multiplexed data information is obtained from themultiplexed data. Next, in Step exS101, it is determined whether or notthe stream type or the video stream attribute information indicates thatthe multiplexed data is generated by the moving picture coding method orthe moving picture coding apparatus in each of embodiments. When it isdetermined that the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of embodiments, in Step exS102, decoding is performed by the movingpicture decoding method in each of embodiments. Furthermore, when thestream type or the video stream attribute information indicatesconformance to the conventional standards, such as MPEG-2, MPEG-4 AVC,and VC-1, in Step exS103, decoding is performed by a moving picturedecoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard is input, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in the present embodiment can be used inthe devices and systems described above.

Embodiment 5

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 40 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AV10 ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recordingmedium ex215. When data sets are multiplexed, the data should betemporarily stored in the buffer ex508 so that the data sets aresynchronized with each other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present inventionis applied to biotechnology.

Embodiment 6

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of embodiments isdecoded, compared to when video data that conforms to a conventionalstandard, such as MPEG-2, MPEG-4 AVC, and VC-1 is decoded, theprocessing amount probably increases. Thus, the LSI ex500 needs to beset to a driving frequency higher than that of the CPU ex502 to be usedwhen video data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 41illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 40.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 40. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, the identification information described inEmbodiment 4 is probably used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment 4 but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 43. The driving frequency can be selected by storing the look-uptable in the buffer ex508 and in an internal memory of an LSI, and withreference to the look-up table by the CPU ex502.

FIG. 42 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofembodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set to a voltage lower than that in the case where the drivingfrequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG-4 AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of embodiments, the driving frequency isprobably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of embodiments, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set higher. When the identification information indicates thatthe video data conforms to the conventional standard, such as MPEG-2,MPEG-4 AVC, and VC-1, the voltage to be applied to the LSI ex500 or theapparatus including the LSI ex500 is probably set lower. As anotherexample, when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of embodiments, the drivingof the CPU ex502 does not probably have to be suspended. When theidentification information indicates that the video data conforms to theconventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1, the drivingof the CPU ex502 is probably suspended at a given time because the CPUex502 has extra processing capacity. Even when the identificationinformation indicates that the video data is generated by the movingpicture coding method and the moving picture coding apparatus describedin each of embodiments, in the case where the CPU ex502 has extraprocessing capacity, the driving of the CPU ex502 is probably suspendedat a given time. In such a case, the suspending time is probably setshorter than that in the case where when the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG-4 AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Embodiment 7

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a cellular phone. In order to enable decoding theplurality of video data that conforms to the different standards, thesignal processing unit ex507 of the LSI ex500 needs to conform to thedifferent standards. However, the problems of increase in the scale ofthe circuit of the LSI ex500 and increase in the cost arise with theindividual use of the signal processing units ex507 that conform to therespective standards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 are partly shared. Ex900 in FIG. 44A showsan example of the configuration. For example, the moving picturedecoding method described in each of embodiments and the moving picturedecoding method that conforms to MPEG-4 AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. The details ofprocessing to be shared probably include use of a decoding processingunit ex902 that conforms to MPEG-4 AVC. In contrast, a dedicateddecoding processing unit ex901 is probably used for other processingwhich is unique to an aspect of the present invention and does notconform to MPEG-4 AVC. Since the aspect of the present invention ischaracterized by inter prediction in particular, for example, thededicated decoding processing unit ex901 is used for inter prediction.Otherwise, the decoding processing unit is probably shared for one ofthe entropy decoding, inverse quantization, deblocking filtering, andmotion compensation, or all of the processing. The decoding processingunit for implementing the moving picture decoding method described ineach of embodiments may be shared for the processing to be shared, and adedicated decoding processing unit may be used for processing unique tothat of MPEG-4 AVC.

Furthermore, ex1000 in FIG. 44B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to an aspect of the present invention, a dedicated decodingprocessing unit ex1002 that supports the processing unique to anotherconventional standard, and a decoding processing unit ex1003 thatsupports processing to be shared between the moving picture decodingmethod according to the aspect of the present invention and theconventional moving picture decoding method. Here, the dedicateddecoding processing units ex1001 and ex1002 are not necessarilyspecialized for the processing according to the aspect of the presentinvention and the processing of the conventional standard, respectively,and may be the ones capable of implementing general processing.Furthermore, the configuration of the present embodiment can beimplemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding methodaccording to the aspect of the present invention and the moving picturedecoding method in conformity with the conventional standard.

INDUSTRIAL APPLICABILITY

The present disclosure is used for the moving picture coding apparatusand the moving picture decoding apparatus. For example, the presentdisclosure is applicable to information display device and imagingdevice such as television, digital video recorder, car navigationsystem, mobile phone, digital still camera, digital video camera, andothers.

The invention claimed is:
 1. A moving picture decoding method fordecoding a current block to be decoded included in a current picture tobe decoded by inter predictive decoding using a motion vector, themoving picture decoding method comprising: decoding a first flagindicating whether or not temporal motion vector prediction using atemporal motion vector predictor which is a motion vector of a blockincluded in a decoded picture different from the current picture isused; assigning one or more reference picture indexes to a referencepicture list; when the first flag indicates that the temporal motionvector prediction is used, decoding a collocated reference picture indexfor specifying the decoded picture among a plurality of picturesindicated by the one or more reference picture indexes, deriving aplurality of first motion vector predictor candidates including (i) aspatial motion vector predictor which is a motion vector of a blockadjacent to the current block in the current picture and (ii) thetemporal motion vector predictor, the temporal motion vector predictorbeing calculated based on a motion vector of the coded picture which isspecified by the collocated reference picture index, and decoding amotion vector used for performing inter predictive decoding on thecurrent block using one of the first motion vector predictor candidates;and when the first flag indicates that the temporal motion vectorprediction is not used, deriving a plurality of second motion vectorpredictor candidates that do not include the temporal motion vectorpredictor, the second motion vector candidates including (i) the spatialmotion vector predictor and (ii) a replacement vector, as a replacementfor the temporal motion vector predictor, which has a value of zero, anddecoding a motion vector used for performing inter predictive decodingon the current block, using one of the second motion vector predictorcandidates, wherein when the first flag indicates that the temporalmotion vector prediction is not used, the collocated reference pictureindex is not decoded.
 2. The moving picture decoding method according toclaim 1, the moving picture decoding method being for decoding picturesbelonging to a base view and a dependent view in a multi-view video, themoving picture decoding method further comprising generating a disparityvector corresponding to disparity between the base view and thedependent view, wherein in deriving the second motion vector predictioncandidates, the disparity vector is included in the second motion vectorprediction candidates as the replacement vector.
 3. A moving picturedecoding apparatus comprising: a control circuitry; and a storageaccessible to the control circuitry, wherein the control circuitryexecutes the moving picture decoding method according to claim 1.